@KitRedgrave Probably the latter, honestly; ever since social media became the predominant way of meeting new folks online the dynamics around that whole thing changed a lot, people have gotten way pickier about who they choose to interact with and that just doesn't work together well with a MUCK.
@KitRedgrave It's the same reason IRC just isn't that big a thing anymore - back then a channel was pretty much a community all of its own and you couldn't really choose to speak only to the people you wanted to in there, without resorting to making a whole new channel of your own and inviting them into it. It was an all or nothing kind of deal, bad actors who are well-liked enough by the admins to be kept around included.
@KitRedgrave You do!
You also see lots and lots of people complaining about those - often with the exact same complaints people had about IRC channels back in the day ("it's full of assholes/people with reprehensible viewpoints/the rules are completely nonsensical/etc").