Spam-detectors, bot-detector and -banning tools, developers of the former three, powerusers. They all went when reddit shot itself in the head.
Now reddit is bleeding out, flooded by spam and bots, quality decreasing every day. These people will probably not come back, no matter what reddit does now.
It was restricted for about a month, I think, after being private for a couple of weeks. When it's restricted, you can see posts and comments, but you can't make any new ones. It's kind of a middle ground between being open and private.
I don't know if it's actually related but I've definitely seen far fewer posts from 196 since then. It used to be all over all my feeds. Now I barely see it even on my subscribed view.