My long hiatus started a couple years ago, so my perspective might be different from yours.

I think the main issue for me it was more that it wasn't very fun any more. The people who made it fun (EY, Yvain, etc) were mostly posting elsewhere. The majority of posts were starting to be boring things like meetup announcements. Some of the new posts were interesting, but had more technical content and less humor.

Part of it could be that the commenters became more politically (in the sense of national politics) motivated, but that's not something I noticed at the time... I think that's perhaps a more recent thing, assuming that is indeed happening.

Another thing that might have been a factor is that I started using a smartphone more. So apps like twitter and facebook that can be easily checked there had more appeal. (This website still sucks for mobile.)