I've documented in other threads that a focus on canon, and how/whether pieces of fiction "count" and fit together in a shared continuity, is a practice that stretches back decades.
Of course it is. Greg wasn't claiming otherwise. His point wasn't about the existence of continuity, but about modern fandom's preoccupation with it as an all-consuming priority, rather than just one option for telling stories.
...but the entire point of my previous post is that there is a spectrum of "laissez-faire" to "100% consistency," that franchises establish where they fall on that spectrum, and that audiences will adjust their expectations accordingly.
It would be unrealistic to expect a franchise that endures over decades and is created by a variety of different teams would remain perpetually unchanging in its approach. Every recurring theme can be expressed through many different variations; indeed, exploring those variations is an integral part of the creative process. Creators don't adopt existing themes to slavishly copy exactly what their predecessors did with them, but to find a new way to develop them that retains their essence while finding different layers within them.
A number of people in this very thread have essentially argued that Discovery couldn't possibly stick to the same visual aesthetic because makeup/set design/technology have advanced over time--as if we haven't seen other franchises (and Star Trek itself) do just that.
"Couldn't" is not what was argued. Nobody was saying that later creators were unable to recreate past designs -- we were saying it was understandable why the creators would find it desirable to take advantage of the increased potential that more advanced prosthetic technology made possible. Greg's point, specifically, was that a choice was made to replicate the effect of older designs rather than merely the superficial appearance thereof, because that appearance would not have the same impact on modern audiences who've seen so many other sophisticated makeup designs and would be less impressed by the old ones.
It makes no sense to cast creative discussions in terms of concepts like can/can't or should/shouldn't. Creativity is about individual choice, not physical laws or mandatory doctrines. The point is not to say that anything had to be done a certain way, just to say that it was done for a reason that made sense to the people who did it, even if you or I didn't like the result.
Again, you've already done a fantastic job articulating why it was artistically arbitrary to set this story in the TOS era, so marketing the nostalgia seems to have been a primary motivation--and if they wanted to market specifically to the audience for the Kelvin Timeline films, then (from that narrow perspective, at least) it was a mistake not to set this in that continuity instead of marketing one and producing the other.
I find it so bizarre the way some people think nostalgia or continuity is exclusively about visual design. The nostalgia came from the stories and characters and references. Most people care more about those than about how things look. They understand that a changed look is an update for the sensibilities of modern audiences, because most people don't want their futuristic space shows to look like they were made 50 years ago.
So no, of course they didn't want to "market specifically to the audience for the Kelvin Timeline films" -- except in the sense that both recent incarnations of Trek are independently marketed toward contemporary audiences who are used to spectacular, state-of-the-art visuals in their science fiction.