Uh, wow. So this thread is a trip. I had wanted to comment earlier but when I went from the first... 15 or so pages and skipped to here, I had no clue how the heck we drifted so far. Spent the rest of the early morning trying to catch up. Anyways...
To comment on the original topic of the thread: on one level, I am kind of sympathetic to a few of his viewpoints. I do think some of the stating of monsters is just... weird and unnecessary? Like, yeah, it's weird that the Guard Captain (CR 4) need be Strength 18 when you could just as well make him a lesser strength and just give him a higher proficiency or just... I dunno, put in numbers that look right. I get that they have a formula, but it feels that sometimes they were trying too hard to stay within the formula when the last few editions have been specifically about getting away from justifying stuff with stats. At a certain level, this also feels like a problem with naming: the Bandit Crime Lord is probably closer to a legendary Bandit Lord, someone who is an amazing adventurer in and of themselves, hence why they are a CR11 on their own. It's a problem with the framing more than the stats themselves, in my opinion.
It isn't necessarily helped by the streamlining of some monsters. I'm going through the MM right now because I have a group of people from work who want to try "D&D" and I'm obliged to let them have a shot despite my misgivings, but I kind of get the idea of "Rend" from a "this moves quick" even if you lose definition. At the same time, some monsters kind of get hit bad with it (Hobgobbos really feel like they got made duller by giving them pack tactics. Congrats, y'all are now just super-Kobolds. lol) while others I think I like more. I will say that they while he talks about how things are more epic magic fantasy, taking away a lot of the mundane damage immunities honestly helps move away from "You need a +1 weapon to stand a chance", and a lot of physical resistances got saved for things that are either liquids or gaseous. Good move there.
I also get the complaint about the overuse of magic as an explanation about everything; I really dislike that more things have become spells rather than less. I understand why, but I really disagree with it. But one of the big cruxes of his argument, that the power creep is bad, I disagree with. If anything, I'm glad that things are more consistent across classes. Still not to what I want, but it's definitely an improvement. Like, yeah, I understand the frustration of having to get your Patron at 3rd level, but unless you were okay with completely doing away with multiclassing as we know it in 5E, the change was needed because of how powerful dips were.
With that said, where the topic has gone... I dunno, as a forever GM, I feel way more inclined to try and collaborate with my players and get to where they want their concept rather than stifle it. Admittedly when I build a world or merely run a world, I'm okay with exceptions and oddities instead of hard, hard rules on what you can and can't be unless it's agreed on that the campaign is going to be something very specific. For example, in my most recent Pathfinder 2E game, someone wanted to be a goofy Tortle druid. The problem is that, as far as I can tell, there really aren't turtle-people in Golarion (or at least, any with PC stats that I can use). But I was okay with this; there were places in the world that people didn't go that he could be from (We chose the Sodden Lands) and even he didn't know his origins. I used a Titan Nagaji heritage as a background (Makes him slower but well-armored, which fit) and told him that we could talk about sticking with Nagaji or Iruxi (PF Lizardfolk) traits for future upgrades. It worked out fine, and I was very happy that my player got to enjoy that character.
Now have I told players they couldn't do something? Yes, but only when it was relevant to a game plot. My first 5E campaign I had a player who wanted to be a drow, but in my homebrew world, "drow" were not a real race: they were basically a myth created over time around non-elves seeing a secret elvish civil war ("Drow" was a bastardization of the archaic elvish word for "Imperial", and the "Drow" were Lawful elves who wanted to basically 'guide' the 'lesser races' secretly towards a more orderly world). All elves knew this, but they didn't share that information with outsiders. Knowing this, he made himself a Half-Elf and we moved on. But it was not something I simply shut down, it was something I had an in-world explanation for that he found satisfying. If he hadn't... maybe we would have worked something out further. It wasn't just a random world-building aspect, but something that was going to come up over time.
Ultimately, I think I'm just more okay with making that sacrifice myself. Now obviously there are limits to how far you can go, but I think it's way more interesting to try and make a player's concept work than try to water it down because it didn't fit your initial vision of the world.