PG runs a discussion site. He's using it as a sort of wide-flung net to catch worthy candidates for the "inner circle" - startup founders who get into his YC program - and is quite open about it (e.g. he explicitly says that YC submissions will among other things be judged on how well their authors are known as HC commenters and how worthy their comments have been judged to be). Why is it surprising that this creates a cult atmosphere of sorts?

Before Hacker News, PG was already famous in the relevant community for his essays, which are often credited, among other things, for the modern revival of interest in Lisp (this is probably an exaggeration). Nobody called him a cult leader back then.

Joel Spolsky is a famous blogger in the programming/CS/IT niche; he has an active discussion forum on his site. Lots of people respect him, lots of other people look down on his posts. Nobody calls him a cult leader.

RMS doesn't even have a discussion forum, and doesn't write a blog. He browses the web through an email-mediated wget; that's not even Web 1.0, it's Web -0.5 or something. He's widely considered to be a cult leader.

I'd guess that to make people think you're behaving like a cult leader, you need some or all of the following:

1. An ideological commitment that is seen as overriding most other priorities. Something that no matter what other things you're talking about, much of the time you're still really talking about that. Something that, from the perspective of someone not as committed as you are, you won't shut up about.

   Paul Graham won't shut up about startups and how they're the natural way of existing for a talented programmer or entrepreneur. Stallman won't shut up about free software and how you're ethically bound to call your OS GNU/Linux. You won't shut up about Topics that Won't Be Named and a few other things.

2. Actually being a leader or being thought a leader; having a real or widely imagined amount of influence. PG determines who gets into the very prestigious - in the relevant community - YC program. RMS controls GNU and has huge mindshare among free software enthusiasts. Within the admittedly smaller community at OB, you're seen as the most active blogger/proprietor, and the one most involved in its community formation. Unlike Hanson, who's opinionated but detached, you're opinionated and very attached. After lurking at OB for a year or so, I couldn't possibly tell who among the commenters are Hanson's friends, colleagues or fierce antagonists.

3. You need to be seen as molding the community, or your audience, to your liking - either by filtering the undesirables, or boosting the voices of the desirable. In other words, you need to be seen as growing "the cult", sometimes with active choices, sometimes simply by choosing the rhetoric or the content that'll repel the unfaithful.

   PG acts, actively and passively, to limit the total audience of even the outwardly inclusive HN. The theme of keeping HN 'small' so it doesn't deteriorate to the level of Reddit is reiterated by PG and widely shared by the audience. RMS is famous for his attempts to enforce ideological purity. You're explicitly engaged in conscious community-building, which you sometimes describe as leading to a new generation of rationalists which will embrace the Topics that Shall Not be Named. That is, you can be seen (I'm not saying that must necessarily be the case) as not merely hoping to draw an audience of people interested in rational thinking, but actually filtering that audience to a subset that substantially shares your commitment to the Cause.

4. This is an anti-property of being considered a cult leader: actively inviting and nurturing disagreement with yourself. In a blog format, that can work by explicitly encouraging dissent through various stylistic and content-based clues, by being especially mindful of dissenting voices in comments, etc. PG, as far as I could notice, never discouraged criticism and handled it superbly, so he possesses this anti-property (and is consequently much less of a cult leader than he could be otherwise). I hesitate to say I've never seen RMS change his opinion as a result of an argument - I guess this happened a few times on very technical issues - but it's a rare exception. You, while not discouraging criticism at all, are prone to ignore criticism (not mere trolling, but serious criticism) in comments and talk over it with people who mostly agree with you; you're also prone to present criticism against you as a result of a trendy choice to stand up to a perceived cult leader (this is a dangerous stance for oneself to adopt, even when true).