Comment by bobajeff

I think you might be onto something with the observation about people moving from old forum software like phpbb to subreddits.

It's like what happened to personal websites when things like Blogger, Tumblr and Facebook popped up.

It's hard to beat something that is easy to set up and pays for hosting but still let's you control moderation. It's a no brainer.

Managing your own domain where users post content is a minefield of problems these days even if you didn't mind the cost of running it.

Something like this might also explain the move to things like Discord over IRC.