Let's not forget the Eternal September that ruined newsgroups.
I don't think it's really an age issue per se. The problem that a group/demographic/tribe/whatever makes a place hot, then a bunch of people that don't fit their description show up wanting to get in on the fun. The result is the original group packing up and moving on. You see this everywhere from Facebook to gentrifying neighborhoods.
I presume the change in tone and content on reddit is due to mobile users moving to the site. It is probably good for their click rates actually, but discussions were a lot more relaxed 5 years ago. I still use it, but only for niche subs.
I always rolled my eyes at people denouncing the quality of default subs. They weren't good but also not that terrible. Now it isn't necessarily terrible, but just extremely stupid. Nearly every comment.
Well over the last 5 years or so it's just got more commercially focussed - mainstream, populist, more tracking through app use = more advertising dollars. It's just the shift towards full commercial focus.
Things get popular : someone decides to use it to increase their wealth.
I don't think it's really an age issue per se. The problem that a group/demographic/tribe/whatever makes a place hot, then a bunch of people that don't fit their description show up wanting to get in on the fun. The result is the original group packing up and moving on. You see this everywhere from Facebook to gentrifying neighborhoods.