Because no one at Yahoo (or Verizon) cares what happens here. Community moderation doesn't work-- it never has on any other sites, in my experience -- so various categories have been taken over by trolls or hostiles, and there's no one from whom to get help. No one ever responds to pleas for help.
Aside from that problem, the site is just creaky and the problems aren't corrected. We aren't getting emails about anything (I'm not), and now we're not getting notifications. No one seems to be bothering with serious maintenance or updating.
If the site owners don't care, a site is going to deteriorate, and that's precisely what's happened. I keep expecting YA to be shut down altogether. That might be the best thing.