Remember there use to be celebrity websites, fans use to create websites for their favourite celebs? Not anymore. Now you only see celebrity profiles and bunch of fanpages posting same content all over again.
It's almost an inversion - instead of many community sites, there are many users together on a smaller number of community groups, which are generally built on social platforms such as reddit and Facebook which make it easy to create them. It's not necessarily a bad thing, except that the most invested people in the communities don't have ownership of the platform or the data, so the communities that matter to them are vulnerable to any arbitrary changes in what the platform owners choose to do.
I frequent Youtube a ton and I noticed there are distinct communities on there like "Car Youtube" or "Gaming Youtube", hell there's entire communities built up around busting scammers on Instagram (those guys posting with stack of cash and a Lambo).
You start watching one channel and realize these guys do colabs with others in that space. Just a few months ago 3-4 Car Youtubers I watch got together and created "CarTrek" which is like a full blown TopGear esque car show.