All right, I'll give it a try (cc @Said Achmiz).

Enforcing norms of any kind can be done either by (a) physically preventing people from breaking them—we might call this "hard enforcement"—or (b) inflicting unpleasantness on people who violate said norms, and/or making it clear that this will happen (that unpleasantness will be inflicted on violators), which we might call "soft enforcement".^[1]

Bans are hard enforcement.  Downvotes are more like soft enforcement, though karma does matter for things like sorting and whether a comment is expanded by default, so there's some element of hardness.  Posting critical comments is definitely soft enforcement; posting a lot of intensely critical comments is intense soft enforcement.  Now, compare with Said's description elsewhere:

On Less Wrong, there are moderators, and they unambiguously have a multitude of enforcement powers, which ordinary users lack. Ordinary users have very few powers: writing posts and comments, upvotes/downvotes, and bans from one’s posts.

Writing posts and comments isn’t anything at all like “enforcement” (given that moderators exist, and that users can ignore other users, and ban them from their posts).

Said is clearly aware of hard enforcement and calls that "enforcement".  Meanwhile, what I call "soft enforcement", he says isn't anything at all like "enforcement".  One could put this down to a mere difference in terms, but I think there's a little more.

It seems accurate to say that Said has an extremely thick skin.  Probably to some extent deliberately so.  This is admirable, and among other things means that he will cheerfully call out any local emperor for having no clothes; the prospect of any kind of social backlash ("soft enforcement") seems to not bother him, perhaps not even register to him.  Lots of people would do well to be more like him in this respect.

However, it seems that Said may be unaware of the degree to which he's different from most people in this^[2].  (Either in naturally having a thick skin, or in thinking "this is an ideal which everyone should be aspiring to, and therefore e.g. no one would willingly admit to being hurt by critical comments and downvotes", or something like that.)  It seems that Said may be blind to one or more of the below:

• That receiving comments (a couple or a lot) requesting more clarification and explanation could be perceived as unpleasant.
• That it could be perceived as so unpleasant as to seriously incentivize someone to change their behavior.

I anticipate a possible objection here: "Well, if I incentivize people to think more rigorously, that seems like a good thing."  At this point the question is "Do Said's comments enforce any norm at all?", not "Are Said's comments pushing people in the right direction?".  (For what it's worth, my vague memory includes some instances of "Said is asking the right questions" and other instances of "Said is asking dumb questions".  I suspect that Said is a weird alien (most likely "autistic in a somewhat different direction than the rest of us"—I don't mean this as an insult, that would be hypocritical) and that this explains some cases of Said failing to understand something that's obvious to me, as well as Said's stated experience that trying to guess what other people are thinking is a losing game.)

Second anticipated objection: "I'm not deliberately trying to enforce anything."  I think it's possible to do this non-deliberately, even self-destructively.  For example, a person could tell their friends "Please tell me if I'm ever messing up in xyz scenarios", but then, when a friend does so, respond by interrogating the friend about what makes them qualified to judge xyz, have they ever been wrong about xyz, were they under any kind of drugs or emotional distraction or sleep deprivation at the time of observation, do they have any ulterior motives or reasons for self-deception, do their peers generally approve of their judgment, how smart are they really, what were their test scores, have they achieved anything intellectually impressive, etc.  (This is avoiding the probably more common failure mode of getting offended at the criticism and expressing anger.)  Like, technically, those things are kind of useful for making the report more informative, and some of them might be worth asking in context, but it is easy to imagine the friend finding it unpleasant, either because it took far more time than they expected, or because it became rather invasive and possibly touched on topics they find unpleasant; and the friend concluding "Yeesh.  This interaction was not worth it; I won't bother next time."

And if that example is not convincing (which it might not be for someone with an extremely thick skin), then consider having to file a bunch of bureaucratic forms to get a thing done.  By no means impossible (probably), but it's unpleasant and time-consuming, and might succeed in disincentivizing you from doing it, and one could call it a soft forbiddance.^[3] (See also "Beware Trivial Inconveniences".)

Anyway, it seems that the claim from various complainants is that Said is, deliberately or not, providing an interface of "If your posts aren't written in a certain way, then Said is likely to ask a bunch of clarifying questions, with the result that either you may look ~unrigorous or you have to write a bunch of time-consuming replies", and thus this constitutes soft-enforcing a norm of "writing posts in a certain way".

Or, regarding the "clarifying questions need replies or else you look ~unrigorous" norm... Actually, technically, I would say that's not a norm Said enforces; it's more like a norm he invokes (that is, the norm is preexisting, and Said creates situations in which it applies).  As Said says elsewhere, it's just a fact that, if someone asks a clarifying question and you don't have an answer, there are various possible explanations for this, one of which is "your idea is wrong".^[4]  And I guess the act of asking a question implies (usually) that you believe the other person is likely to answer, so Said's questions do promulgate this norm even if they don't enforce it.

Moreover, this being the website that hosts Be Specific, this norm is stronger here than elsewhere.  Which... I do like; I don't want to make excuses for people being unrigorous or weak.  But Eliezer himself doesn't say "Name three examples" every single time someone mentions a category.  There's a benefit and a cost to doing so—the benefit being the resulting clarity, the cost being the time and any unpleasantness involved in answering.  My brain generates the story "Said, with his extremely thick skin (and perhaps being a weird alien more generally), faces a very difficult task in relating to people who aren't like him in that respect, and isn't so unusually good at relating to others very unlike him that he's able to judge the costs accurately; in practice he underestimates the costs and asks too often."

1. ^{^}

   And usually anything that does (a) also does (b).  Removing someone's ability to do a thing, especially a thing they were choosing to do in the past, is likely unpleasant on first principles; plus the methods of removing capabilities are usually pretty coarse-grained.  In the physical world, imprisonment is the prototypical example here.

2. ^{^}

   It also seems that Duncan is the polar opposite of this (or at least is in that direction), which makes it less surprising that it'd be difficult for them to come to common understanding.

3. ^{^}

   There was a time at work where I was running a script that caused problems for a system.  I'd say that this could be called the system's fault—a piece of the causal chain was the system's policy I'd never heard of and seemed like the wrong policy, and another piece was the system misidentifying a certain behavior.

   In any case, the guy running the system didn't agree with the goal of my script, and I suspect resented me because of the trouble I'd caused (in that and in some other interactions).  I don't think he had the standing to say I'm forbidden from running it, period; but what he did was tell me to put my script into a pull request, and then do some amount of nitpicking the fuck out of it and requesting additional features; one might call it an isolated demand for rigor, by the standards of other scripts.  Anyway, this was a side project for me, and I didn't care enough about it to push through that, so I dropped it.  (Whether this was his intent, I'm not sure, but he certainly didn't object to the result.)

4. ^{^}

   Incidentally, the more reasonable and respectable the questioner looks, that makes explanations like "you think the question is stupid or not worth your time" less plausible, and therefore increases the pressure to reply on someone who doesn't want to look wrong.  (One wonders if Said should wear a jester's cap or something, or change his username to "troll".  Or maybe Said can trigger a "Name Examples Bot", which wears a silly hat, in lieu of asking directly.)