Thank you for articulating this. I've noticed these kinds of comments are common on reddit, and since becoming a mod of a reasonably popular subreddit they've irked me, but I allowed them in the interest of free-ish speech/not wanting to be authoritarian, and also because I couldn't articulate exactly what the problem was. After all, I didn't think criticism of a given subreddit was categorically bad.

This:

> It's also a way of keeping one's distance from others: I'm not really part of this icky group—I'm here, but I'm better.

is a brilliant way of putting it. Completely nails the impression. It's a passive-aggressive, condescending way of pushing yourself up by putting others down.