And there is other precedent, as well. Straight from the original author of the campaigns… errr scenarios, I mean. Notice this thread title by Filthydelphia himself, from 2019, I just came across when researching something else:
And this other thread he made from 2021:
So, apparently, the big corporate false-advertising campaign to swindle us all began over four years ago, by the author himself?
On the contrary, in reading his thread titles and through his posts, it seems pretty clear he innocently (and as we now learn, probably accidentally, from a vernacular or colloquial standpoint?) used campaign and scenario interchangeably. And I see in those threads that fellow players used the terms interchangeably, as well! I haven’t looked through them all, but I didn’t find any posts yet where fans call him out on it.
I find it funny, though, that I was confused at the time (four years ago) about not being able to proceed to the next scenario after completing a scenario, as I was used to multi-mission/multi-scenario campaigns. Filthydelphia replied and helped me understand his creations better! 
Interestingly, he told me: “It’s a single scenario campaign”. (Basically, using them in a manner which indicates he felt they are, technically, campaigns, but only single-scenario ones)…
I think his description of “single scenario campaigns” is not, necessarily, wrong… and is a nice, succinct way of how I felt Marketing was probably labeling his creations. Because the scenarios do exist under the Campaign button, after all. (Going back to, possibly, all this being an honest mistake rather than a malicious bait-and-switch or sleight-of-hand trick to swindle us.)
cc: @Quasibrodo