I think it makes sense that they comment primarily on the bigger posts, because those posts are predominantly written by those people that have been around a while - their old friends

I comment predominantly on posts from people I know through communities such as thealliance or theunmentionables. A year or 18 months ago, when the site was much smaller, I imagine it effectively was one single community in the same way, and so these people have grown with it and maintained their original relationships

The communities give us an opportunity to turn back the clock

Cheers