Whoa. Comp.arch. I learned so much from that during 90s. There's nothing like debates with anecdotes thrown between experienced folks to learn from, and comp.arch back then had such a high signal-noise ratio that it was amazing.
I'm not a social media expert, but with mastadon, blue sky, discord, even reddit (although perhaps the latter is now on a downward spiral; slashdot used to be one such too) with their specialised servers/forums etc, maybe there are still high signal-to-noise forums (HN is probably one such)