As a zillenial who grew up playing DikuMUD derivatives, LPMUDs, and MUs, I feel uniquely qualified to bridge the gap here.

What GP is referring to and complaining is that when people say MUD, they're probably referring to either:

- A MUD based on some derivative of the TinyMUD codebase, colloquially called "MUs"

- Literally any other "MUD"

These two categories of "games" are both legitimately called "MUDs" but also have almost nothing in common with each other. The union of "MU" players and "MUD" players is not that large, in my experience. MU servers tend to function somewhere between glorified Discord servers and sandbox programming environments.

Even more specifically, within the MU* space, the different forks of TinyMUD ended up adopting different subcultures, programming languages, and general vibes. Despite all being superficially similar, telling someone you play a:

- MUSH

- MUCK

- MOO

says a great deal about both you and server. MUCKs are furry subculture for the most part and use Forth for programming, while MUSHes are ... more Star Trek/Lord of the Rings coded. With other weird differences: MUSHes tend to have elaborate mail and Discord-like comm systems built in, MUCKs tend to eschew those in favor of "hanging out in the same virtual room".

IME there isn't this same feeling in "other MUDs". You don't "identify" DikuMUD or LPMUD players in the same way, so I don't think the question makes sense to anyone who isn't a MU* player.

The difference here is almost entirely cultural, since technologically, LPMUDs and MUSH/MOO/MUCKs aren't that dissimilar. But LPMUDs are almost never used the same way, at least I've never seen it.