Is it uncontroversial to say that many (if not most) experienced players and DMs pick up a new edition of D&D and jump into it before absorbing everything in the PhB and DMG, and rely on what came before to fill in the gaps? And that many (if not most) DMs eventually have house rules of various sorts to tailor the game to their own favorite styles - often relying on what they did in past versions, either by RAW or house rule? It feels like a reason why some might like the previously rules-enshrined enjoinment against OOC knowledge-use needs no further justification than comfort with the familiar. (At some point the defense of tradition does seem to back up your argument that it's become an identity issue. But it feels like converts to things are also wont to be overly self assured in their own defense - even moreso than those who have always done that same thing

).
It feels like over the years, in groups I've DM'd and played in, that too-blatant levels of using OOC knowledge have almost never come up. I'm not sure I can remember the last time it came up during play in a way that felt derailing or jarring. Maybe a player asking the DM pre-emptively if everyone in a particular world would know something? That said, It feels like once we've known something regenerates we've always jumped to either acid or fire and the DMs and players all seem to assume that's common knowledge. My memory of 38+ years ago doesn't have how I first learned that fact as a player -- and I can't remember the last time I ran into trolls.
At some point, the rule against using anything that a character wouldn't know gets silly, right? "What do you mean that your character from the desert stops before they get to the edge of the 200' cliff? You've always just jumped down the shorter ones? How does your character know how acceleration and damage work from great heights?"
On the other hand, even some who are ok with OOC knowledge have admitted a place for secret in-game side-bars between the DM and an individual player. If OOC knowledge never matters, why should such side-bars ever be desirable or beneficial? If additional player knowledge never diminishes anything, why should it matter if player A knows player B is planning something character A would object to? Maybe character B will change their mind anyway or has a good reason for doing it!
I wonder how much of it being an issue is how high or low each player and DMs bar of being blatant is (EDIT: see the two posts above this by
@Crimson Longinus and
@Ovinomancer ), and how often that line is crossed once the tables expectations are discussed in session 0.
In any case, I kind of wish the current books mentioned avoiding OOC knowledge use as a playstyle thing some tables have. But the don't-worry-about-it side has convinced me that if the book had to pick one, it's better to leave out mention of OOC knowledge than to forbid its use.