MUDs (still) have perhaps the greatest potential for depth of play, immersive online LARPing, player customization, and long-lasting enjoyment—and because they're almost purely text and code (graphical interpreters aside), you don't have to pay 2 artists, 3 animators, and 5 professional programmers $200,000 to add a few small bits of content. The admins can selectively choose non-cringeworthy players and grant them the ability to write new rooms, characters, items, and so on, which they'll happily do for free.
But much like tabletop RPGs, there are some turds in the punchbowl. For MUDs, it's the fact that it's a dying genre with 95% of the active population concentrated in Iron Realms Entertainment, Simutronics, Tardwolf, and adult-themed MUDs/MUSHes/MU*, with the remaining scraps spread out over all the rest of the MU*s in existence. The genre is completely stagnant. Want to start a new MU*? Good luck with that, there are already dozens and dozens with tiny populations in every flavor you can imagine. That, and the fact that there will always be a percentage of any MU*'s player base comprised of gross attention-whoring hagqueens and entitled fatbeard dweeblords stirring up middle school-caliber drama within the game, because that MUD is literally their social life and their entire self-esteem depends on their imaginary persona. Essentially, the sort of people who never progressed past the emotional age of 12 or so.
Tabletop RPGs suffer from dorky people who just want to sit in a room, make fart jokes, roll some dice, shoot the shit, and essentially play grown-up GI Joes. Tabletop RPGs are supposed to be fun and not historical reenactments, but it's excessively difficult to find people who'll take their fun seriously and put real thought into their characters, into what their characters say and do, and really get invested in the storyline. My vision of playing a tabletop RPG is for the group to create the equivalent of a Ridley Scott film, but a huge quantity just want to make a shitty Michael Bay film with clowns and dragons in it. They want to live out their own casual personal fantasies (I want a tiny blue pet dragon, purple eyes, the ability to wield four lightsabers, etc.), and that's it. Not to mention only playing D&D or World of Darkness, and never anything more complex or obscure.
It's theoretically possible to get four serious players together, and I've done it twice (one group lasted for a year), but it's just too much fucking trouble to find them nowadays.
My expectations of both MUDs and tabletop RPGs were probably far too high, even when I was a teenager. I expect to create a world with other people, a compelling and genuine-feeling jointly-told narrative, but that's excessively rare. Usually it's just a bunch of jerkwads frigging themselves off and giggling around a table.
