I think that by mid-1990s standards MU*s counted, especially MUDs, or places like Arx. There were games like Nettrek that were effectively MUDs, accessed over the internet, were entirely text-based, with economies, ship battles, etc, and IIRC they were called video-games.
I attended a conference in the early 1990s, as well, where people were trying to convert MUs into graphical games-- this was also a pivotal moment (IMO) in the creation of MMOs, which were not quite there yet but folks were trying to apply text-based roleplaying into a graphical medium, both with an arcing plot and personal mini-plots. There was a debate even then whether MUs were videogames.
The pushback from the MU* community was hard: they wanted it to remain text-based, with graphics supplied by our imaginations, as this was considered more immersive than the shitty polygons and awkward interfaces that had currently been sort of available. There was skepticism that you could convert MUers to a multi-gamer entirely graphical system: the beauty of language and creativity would be lost.
Fast-forward to today, and MMOs usually have one RP server where most folks use a mush-like post format to play. It reminds me of early pre-TF posing because of the lack of a larger TF-like and client-like buffer. People sometimes use mods like MRP in WoW to give themselves a description, background, +finger/wiki type deal.
So I'm not sure if by today's standards a MU* is a video-game anymore, but IMO it was by the standards going around back when we first started, especially, as mentioned earlier, heavily-automated formats.