I don’t get it.
D&D is a game. So why do people object to it being treated like a game?
I'm prepared to assert that, to a certain extent, it is about a sense of exclusive
ownership.
Because of its share of the TTRPG player base, D&D has multiple player constituencies with gameplay preferences that are often at odds with each other. That's fine as far as it goes - as long as you (in the general sense) are (a) willing to accept that the attempt to satisfy as many player constituencies as possible won't be especially satisfying to you personally, and (b) willing to share.
To my mind,
being willing to think of D&D as a game at the meta level would also entail accepting the idea that it can be
designed with just the sort of modularity that was discussed during the Next playtest in order to make (a) less onerous (because each player constituency can have rules "modules" that are more
robustly designed to satisfy its preferences) and (b) easier. To my mind there is little to be lost - and much to be gained! - from that sort of mindset.
I don't get the impression that very much of (a) or (b) are happening. What a lot of the anti-game argumentation comes across as is asserting an unwillingness to allow the game to be developed in an effort to better satisfy
anyone else's preferences - even if it could then
also be developed to better satisfy
their own preferences. Likewise, "edition warring" comes across as a plain and simple unwillingness to share the game with other player constituencies.
I am sure the "anti-game" arguers will disagree with this assessment, but, bluntly put, when the rubber hits the road and I advocate for including more gameplay elements that I want to see in the game that aren't there now (or someone else advocates for stuff they're interested in), those same people will be right there to argue that we can't have it because "immersion" or "realism", or what-have-you.
This is not to say that immersion, realism, or whatever else people say motivates them to argue against D&D-as-game aren't also very real motivating factors! But I think if it was
just about immersion (etc.), we wouldn't be getting these debates. I just don't think we can get from "having a set of gameplay preferences with respect to playing D&D" to "continually arguing against other people with different gameplay preferences getting more of what they want out of D&D" without a need or desire to have a sense of exclusive ownership over the game.
Edit to add: I'd also go so far as to assert that part of it is also the natural tendency to treat one's own gameplay preferences as "objective metrics of gameplay quality", at least to a certain extent.
Post 47 in this thread strikes me as an example of this sort of thing. This works together with a sense of ownership. If you're already playing D&D "the best" way it can be played or the way it is "meant" to be played, why would you want to compromise?
To top it off, I'll give an actual video game example where the lack of gamist conceits is what made the game for me. Last week in Baldur's Gate 3, my party triggered a building's self-destruct mechanism, and we needed to get out of the building in 4 turns or die horrible deaths. The game immediately plopped me in turn-based mode, where I got everyone Dashing and jumping to get out as quickly as possible. On the last turn, the party reached a chasm - and if they could somehow safely land, they'd be safe. Incidentally, my Wizard was wearing Boots of Featherfall, so he activated it, after which the Cleric and the Rogue jumped off. However, the Wizard activating the boots and running to the edge of the chasm meant he no longer had the time to jump off. But my Barbarian came right by him, grabbed him and threw him straight on the ground. She then proceeded to jump down herself, and the party safely watched the building crumble.
I don't want to dispute the sincerity, but this
really comes across as special pleading. Like, you had an immersive experience playing a game that is explicitly designed
as a game by people who deliberately design games
as games, using
explicitly gamist mechanics (the turn-based system). But somehow D&D can't be allowed to be more deliberately designed to more robustly support its core player constituencies?
(Also, I must needs point out that the immersivity of video games these days follows from the fact that video game designers have put in an awful lot of work researching and
designing it.)