I played the Iron Realms Entertainment games(mostly Achaea) into the mid-2000s, for kind of the inverse reason of why you didn’t play WoW - I couldn’t afford it, and my internet connection wasn’t good enough for it. But MUDs are free, and you can practically play by whistling down a phone line, so for early-to-mid-2000s Australian internet, that meant I could play on my shitty home connection.
I still check things out every once in a while, though I don’t play any currently, partially for nostalgia, partially because it’s just interesting.
Aside from the bigger players like Iron Realms(who not only have their own cross-platform client, along with browser clients, mobile clients, open connectivity for all other clients, and the ability to connect via terminal if you wish - they’re pretty much the gold star for MUD interfaces), that’s because most MUD players these days use their own clients like TinTin, Atlantis, or Mudlet. No point spending the time and resources - especially considering how thin most of them run - on something that most players already have their own solution for.