I began using reddit in 2017. I never really realized there had been a decline in quality until I recently ended up on some threads from 2017ish. I think some of it had to do with the change from a very desktop-oriented, forum-style page, to a dumbed-down mobile-friendly experience. The emphasis is now heavy on pictures, videos, instant messaging, avatars, online status, shiny award bling, infinite scrolling, etc. Reddit may not have intended it, but I feel like their target age demographic is much lower now. I'm shocked at how many regular users are still in high school or even middle school. I'd guess the kids are the ones repeating the funny jokes en masse. They're just kids being kids, but it gets old sometimes.