Eh, language evolves, terms that follow normal grammar constructions eventually are expanded beyond their niches (see: "forbade" and all those verbs that start with "for"; as well as "embiggen" etc).

"Enshittify" is literally just "make something shittier" ("en-" + "shit" + "-fy"). Sure it was coined for the idiosyncracies of this absurd timeline, and we are all glad for that -- but really it's just a correct word that has always existed it just went unused.

Now, if you want to pedant, sure let's go that way: Mozilla is also a platform that "entices people with a free offering" (Firefox), then "gradually tightens" (or, really, loosens) the screws over time "to make that service worse" (Pocket, Robot, post-Auralis UI, AIs, etc). This "usually happens when a platform becomes the dominant player" (in this case, basically the only big Gecko browser).