Agreed. Forums are tricky because in my experience of you get too many people outside of the niche you’re discussing the quality goes down.
But if you don’t have enough then the Reddit community will take the majority of the discussion away from the forum.
There are some good hobby based ones still out there but discovery is always a challenge. Your best bet is finding someone who’s engaged in discussions you like and seeing where they go for said discussions.
He is on Mastodon @adamconover@mastodon.social though.
And I do agree with the first part of the statement…but I think a good chunk of us here use Linux so the latter part falls flat.
Perhaps we’ll see it similar moreso to Unix. Where activity pub is Unix and is used around the world. But Linux is still used by a small portion of the population.