Well that's a self-reinforcing spiral of a different type. In general, I see a number of forces pushing newcomers to a group towards being similar to whoever the folks already in the group are:
The Iron Law of Bureaucracy, insofar as it's accurate.
Self-segregation. It's less aversive to interact with people who agree with you and are similar to you, which nudges people towards forming social circles of similar others.
Reputation effects. If Google has a reputation for having great programmers, other great programmers will want to work there so they can have great coworkers.
This is why it took someone like Snowden to expose NSA spying. The NSA was the butt of jokes in the crypto community for probably doing illicit spying long before Snowden... which meant people who cared about civil liberties didn't apply for jobs there (who wants to work for the evil empire?) (Note: just my guess as someone outside crypto; could be totally wrong on this one.)
Edit: evaporative cooling should probably be considered related to the bullet points above.
A few notes about the site mechanics
A few notes about the community
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* Normal_Anomaly
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A note for theists: you will find the Less Wrong community to be predominantly atheist, though not completely so, and most of us are genuinely respectful of religious people who keep the usual community norms. It's worth saying that we might think religion is off-topic in some places where you think it's on-topic, so be thoughtful about where and how you start explicitly talking about it; some of us are happy to talk about religion, some of us aren't interested. Bear in mind that many of us really, truly have given full consideration to theistic claims and found them to be false, so starting with the most common arguments is pretty likely just to annoy people. Anyhow, it's absolutely OK to mention that you're religious in your welcome post and to invite a discussion there.
A list of some posts that are pretty awesome
I recommend the major sequences to everybody, but I realize how daunting they look at first. So for purposes of immediate gratification, the following posts are particularly interesting/illuminating/provocative and don't require any previous reading:
More suggestions are welcome! Or just check out the top-rated posts from the history of Less Wrong. Most posts at +50 or more are well worth your time.
Welcome to Less Wrong, and we look forward to hearing from you throughout the site!
Once a post gets over 500 comments, the site stops showing them all by default. If this post has 500 comments and you have 20 karma, please do start the next welcome post; a new post is a good perennial way to encourage newcomers and lurkers to introduce themselves. (Step-by-step, foolproof instructions here; takes <180seconds.)
If there's anything I should add or update on this post (especially broken links), please send me a private message—I may not notice a comment on the post.
Finally, a big thank you to everyone that helped write this post via its predecessors!