It's as if someone came around suddenly and said "Sherlock Holmes of course never took place in our universe! It's ridiculous to think someone in our universe could be that smart and capable! The only logical conclusion is Sherlock takes place in an alternate universe with a different history and human-like aliens. That's just logic!"
It's stupid.
Yes. But
why ? In my view exactly because everyone should
already know this and repeating it is simply an insult to the viewer. It would be much like an action movie, where the lead actor suddenly turns to the screen and says: "you know, you've seen me driving through red traffic light intersections at high velocities and emptying my guns on those I was chasing. In real life, this usually isn't a good idea" It's certainly absolutely true, but it really doesn't need any explaining (
and it breaks immersion).
Pretending Trek takes place in 'our' future would always have been a doomed enterprise as time went on. Those cracks between what the show had to assume about the future and what would actually would happen would have shown after 55 years in any event - unless they would have strictly confined themselves to a remote century and never made any statements about the 20th/21st century - but in that case, there really wouldn't have been any link between our world and their world in the first place. And they made such statements about our time exactly
because Star Trek was meant as a commentary on our time, too. So ultimately the choice would always have been between endless revisions of earlier material or simply giving some indication that this isn't happening in
our timeline- and I'm glad they chose the latter. Had they chosen the 'endless revisions' route I probably would have stopped watching, or start assuming that this was taking place in an alternate timeline from older material anyway (much like many already do with the JJ Abrams material).
So, I think on
both routes it eventually would have become unavoidable to assume an alternate timeline/universe. I prefer the more graceful exit in that case - the open, but subtle admission. Not an actor saying so on the screen, but showing /referring to an event we already know will be (or was) counterfactual.