The point was not to take an extreme stance; it was simply to say that if we were already in a paradigm of extreme...let's call it "DM Latitude", then (very nearly) any change at all would necessarily move away from it. I very much believe that 5.0 went dramatically overboard in pushing the DM-above-all, of treating the player as a mere witness or present only at the intense sufferance of the DM.
Remember that in the wake of 5.0's publication, we really did have a year or two of people on this very forum would respond to every single question--literally every single one--about how the rules work with, "<information> ...unless your DM says otherwise." Because that was the eggshell-fragile presentation of the rules, that was how people understood 5.0 when it was fresh. After a couple of years of that song and dance, we all kind of collectively got over it and realized that treating the rules as a diaphanous nothing wasn't super productive, but the text remained where it was in 2014, as text is so stubbornly wont to do.
So...yeah. I really do believe 5.0 went massively overboard in positioning the DM as absolute, unimpeachable, unquestionable dictator, which the players must meekly submit to under all circumstances. So...anything other than actually saying that explicitly outright would be stepping away from it, to one degree or another. I certainly grant that 5.5e is consciously stepping back from that overwhelming "the DM is absolutely everything, and you the player better shape up or you'll get shipped out" attitude. (Though I will admit, the pearl-clutching and performative horror over the incredibly bland, milquetoast "changes" to Rule Zero was pretty funny.)
Oh, certainly. Hence why I said I cut my losses and departed that game. But when that happened a second time, with a completely different DM, I wised up pretty quickly; I did not wish to risk a third. 5e DMs were, consistently, not interested in receiving player feedback or discussing anything about the campaign proposal other than what part of it I would be allowed to settle into. And yes, I do credit (or perhaps blame?) the presentation and advice in the books for partially encouraging this particular strain of DM thinking. It's why I've been such a vocal critic of "DM Empowerment" over the years, and why I think so little of any argument that remotely takes seriously the idea of "player entitlement". (Indeed, "player entitlement" is probably my second most-hated phrase in all of TTRPG discussion, and only narrowly beaten by the most: "white room". Mostly because they're non-arguments, emotional short-circuits designed to reject any possibility of discussion or alternatives to whatever the person using them thinks.)
The DM making the final call on rules as default has always been part of the game and does not make them a "dictator". I think giving the DM latitude to tweak the rules is one of the main reasons why 5E succeeded where 4E did not, it was also an issue with 3. This whole idea that everyone should play as if you were in a tournament and therefore had to play one explicit way never really worked for a lot of people. With 3 they tried to define every possibility and codify an answer, they could never cover every option and it just led to a lot of page flipping and "I know there's a rule somewhere". With 4 they tried to codify (almost) every action a PC could take as a power which caused it's own issues.
But TSR versions of D&D? The DM absolutely made the final call, often because there were holes you could drive a tarrasque through or because the rules contradicted themselves on a regular basis.
So if we can get together as a group and play a game that works best for us but a little different from a different group? Awesome. We both get to play the game we want. That does, however require flexibility which means different answers to the same question depending on what kind of game you want. It does not, however, make the DM into a dictator.