I'm sorry to break this to you (please don't shoot the messenger) but fiction-based franchises are almost as old as Hollywood itself:
Well, I think the OP's issue is with the usage of the term. Which now becomes an subject of etymology, which, if we start referring to things as a "film franchise" at a later date, we might start applying it to things that fit the definition that arose prior to the use.
However, googling the etymology of the word, the Oxford English Dictionary does say the earliest known use of the noun film franchise is in the 1930s. So that probably isn't retro-active.
OED's earliest evidence for film franchise is from 1933, in Oxnard (California) Daily Courier.
Unfortunately I don't have an account with them, because it looks like there's even a chart for frequency of use over time (which also gets to the heart of the OP's complaint).
https://www.oed.com/dictionary/film-...&tab=factsheet
I don't know if their chart image is a generic placeholder or a preview, but if it's the latter, it does look like there was a stagnation of growth of the term in the 80's and 90's specifically (though not a reduction).
My recollection was referring to things like Friday the 13th or A Nightmare on Elm Street as a "film series" at the time (but retroactively describing them as a "horror franchise"). I suspect, and I might be putting words, or projecting words, like thought-vomit, into the OP's mouth, that there's a crass commercialization associated with the word "franchise" that they really don't like, or maybe it's the assumed need to be open ended and keep going on forever as opposed to just having a few sequels. For example, the Universal's attempt at a Dark Universe that presumably had no soul to them, as opposed to smaller, more concentrated remakes/updates, such as the recent Invisible Man (I assume the former had no soul to them, I actually haven't watched any of the movies in my example. I'm just going off of impressions of reviews. And the OP's username is
From Beyond, so I am tilting towards horror here). But I might be extrapolating too much from the McDonald's association. But I really don't know.