From hanging around in r/redditdev I got an impression there was an exodus of much of the experienced backend team about a year ago when there was so much drama (Kemitche and at least two more people I think). Maybe it has taken some time to get a new one up to speed. Also, A lot of resources seems to be focused lately on developing clients for android and ios.

I get the impression that Reddit has a lot of technical debt that makes developing new features difficult, and would take some major effort to refactor themselves out of