I never thought of usenet as tech focused. There were many areas that were non-tech topics. Sure there was comp.sys., but all the alt. boards and others. Web forums were kind of the spirtual successor, and many of them have subject subforums, but within that most web forums segregate discussion by thread. I find that much more useful since usenet felt like a mailing list of post after post after post. Threads allow me to ignore discussion that aren't relevant to me.

I haven't migrated from web foums to reddit or facebook groups though I'm sure there is much information in those places. I prefer that independent web forums introduce some friction to participating. You have to create an account, and some forums have limits for new members until they reach a certain post count. While the friction is small that does seem to discourage bad behavior a little.

I have easily found forums for subjects I'm interested in, but none of them are tech, so I don't know whether you'll find web forums on current tech subjects.