I think your post is troubling in a couple of ways.
First, I think you draw too much of a dichotomy between "read sequences" and "not read sequences". I have no idea what the true percentage of active LW members is, but I suspect a number of people, particularly new members, are in the process of reading the sequences, like I am. And that's a pretty large task - especially if you're in school, trying to work a demanding job, etc. I don't wish to speak for you, since you're not clear on the matter, but are people in the process of reading the sequences noise? I'm only in QM, and certainly wasn't there when I started posting, but I've gotten over 1000 karma (all of it on comments or discussion level posts). I'd like to think I've added something to the community.
Secondly, I feel like entrance barriers are pretty damn high already. I touched on this in my other comment, but I didn't want to make all of these points in that thread, since they were off topic to the original. When I was a lurker, the biggest barrier to me saying hi was a tremendous fear of being downvoted. (A re-reading of this thread seems prudent in light of this discussion) I'd never been part of a forum with a karma system before, and I'd spent enough time on here to know that I really respected the opinions of most people on here. The idea of my ideas being rejected by a community that I'd come to respect was very stressful. I eventually got over it, and as I got more and more karma, it didn't hurt so much when I lost a point. But being karmassassinated was enough to throw all of that into doubt again, since when I asked about it I was just downvoted and no one commented. (I'm sure it's just no one happened to see it in recent comments, since it was deep in a thread.) I thought that it was very likely that I would leave the site after that, because it seemed to me that people simply didn't care what I had to say - my comments for about two days were met with wild downvoting and almost no replies, except by one person. But I don't think I am the only person that felt this way when ey joined LessWrong.
Edit: Hyperlink messed up.
Edit 2: It just now occurred to me to add this, and I've commented enough in this thread for one person, so I'm putting it here: I think all of the meetup posts are much more harmful to the signal to noise ratio than anything else. Unless you're going to them, there's no reason to be interested in them.
Aside: That sockpuppetry seems to now be an accepted mode of social discourse on LessWrong strikes me as a far greater social problem than people not having read the Sequences. ("Not as bad as" is a fallacy, but that doesn't mean both things aren't bad.)
edit: and now I'm going to ask why this rated a downvote. What does the downvoter want less of?
edit 2: fair enough, "accepted" is wrong. I meant that it's a thing that observably happens. I also specifically mean socking-up to mass-downvote someone, or to be a dick to people, not rolepla...
EDIT: Thanks to people not wanting certain words google-associated with LW: Phyg
Lesswrong has the best signal/noise ratio I know of. This is great. This is why I come here. It's nice to talk about interesting rationality-related topics without people going off the rails about politics/fail philosophy/fail ethics/definitions/etc. This seems to be possible because a good number of us have read the lesswrong material (sequences, etc) which innoculate us against that kind of noise.
Of course Lesswrong is not perfect; there is still noise. Interestingly, most of it is from people who have not read some sequence and thereby make the default mistakes or don't address the community's best understanding of the topic. We are pretty good about downvoting and/or correcting posts that fail at the core sequences, which is good. However, there are other sequences, too, many of them critically important to not failing at metaethics/thinking about AI/etc.
I'm sure you can think of some examples of what I mean. People saying things that you thought were utterly dissolved in some post or sequence, but they don't address that, and no one really calls them out. I could dig up a bunch of quotes but I don't want to single anyone out or make this about any particular point, so I'm leaving it up to your imagination/memory.
It's actually kindof frustrating seeing people make these mistakes. You could say that if I think someone needs to be told about the existence of some sequence they should have read before posting, I ought to tell them, but that's actually not what I want to do with my time here. I want to spend my time reading and participating in informed discussion. A lot of us do end up engaging mistaken posts, but that lowers the quality of discussion here because so much time and space has been spent battling ignorance instead of advancing knowledge and dicussing real problems.
It's worse than just "oh here's some more junk I have to ignore or downvote", because the path of least resistance ends up being "ignore any discussion that contains contradictions of the lesswrong scriptures", which is obviously bad. There are people who have read the sequences and know the state of the arguments and still have some intelligent critique, but it's quite hard to tell the difference between that and someone explaining for the millionth time the problem with "but won't the AI know what's right better than humans?". So I just ignore it all and miss a lot of good stuff.
Right now, the only stuff I can be resonably guaranteed is intelligent, informed, and interesting is the promoted posts. Everything else is a minefield. I'd like there to be something similar for discussion/comments. Some way of knowing "these people I'm talking to know what they are talking about" without having to dig around in their user history or whatever. I'm not proposing a particular solution here, just saying I'd like there to be more high quality discussion between more properly sequenced LWers.
There is a lot of worry on this site about whether we are too exclusive or too phygish or too harsh in our expectation that people be well-read, which I think is misplaced. It is important that modern rationality have a welcoming public face and somewhere that people can discuss without having read three years worth of daily blog posts, but at the same time I find myself looking at the moderation policy of the old sl4 mailing list and thinking "damn, I wish we were more like that". A hard-ass moderator righteously wielding the banhammer against cruft is a good thing and I enjoy it where I find it. Perhaps these things (the public face and the exclusive discussion) should be separated?
I've recently seen someone saying that no-one complains about the signal/noise ratio on LW, and therefore we should relax a bit. I've also seen a good deal of complaints about our phygish exclusivity, the politics ban, the "talk to me when you read the sequences" attitude, and so on. I'd just like to say that I like these things, and I am complaining about the signal/noise ratio on LW.
Lest anyone get the idea that no-one thinks LW should be more phygish or more exclusive, let me hereby register that I for one would like us to all enforce a little more strongly that people read the sequences and even agree with them in a horrifying manner. You don't have to agree with me, but I'd just like to put out there as a matter of fact that there are some of us that would like a more exclusive LW.