RSS is great for content consumption. It’s a shame that many sites stopped serving it- same thing with podcasts, now everyone wants you to listen on this or that platform instead of just publishing a normal RSS feed full of MP3 files.
That said though, RSS doesn’t help for participation, it’s a one-way tech.
I guess if you have forums that put out RSS feeds you could aggregate them together for post titles, but that’s still clumsy. Lemmy does it much more elegantly.