It's interesting, I just checked it out (I'd never heard of it before) and a number of the usernames seem familiar, and are not who I'd think of as more political-oriented people. The topics are actually more technical and arguably interesting than what shows up on HN these days.

I think it may just be that beyond a certain size, online communities break, and you get crap. And laarc is effectively a splinter off HN of users who got fed up with the content here.