I think the big change has been a shift to massive platforms for everything - so before you'd have hundreds of little vBulletin forums, IRC servers etc.

Nowadays the vBulletin forums have been replaced by subreddits, the IRC servers by Discord channels etc.

It's concentrated the people all in these few platforms which then gives the platform owners (and subreddit/channel moderators) an incredible amount of power and just made everything feel more homogenous and corporate.