The talking points the h4ters used in the edition war were repeated ad nauseum, and the only thing you're likely to accomplish by repeating them (at least, without some new insight, like the OP had) is to tar yourself with the h4ter brush.
Case in point. If you don't want to look the part of the h4ter, don't run so many plays from their book.
Sure, sure. And, you'll note there's virtually no edition warring going on in the 5e discussion group (at least, not against 5e).
The situation you cite was far more the case during the edition war. Fans of 3.x who felt all betrayed not only had a vast wealth of already-published material to draw upon, but the prospect of ongoing support from 3pps in perpetuity. Yet they actively warred against the current edition.
Now that 4e is dead, the only edition of the game that is both unsupported by WotC, and can't legally be cloned by anyone else,
the h4ter edition warring continues.
How terrified do you have to be of something to keep shooting it in the back after it's bled out?
Really, it's designed to be closer to the classic game: it leaves a lot of 3e-isms on the floor, too. (One of the ironies of the edition war is that 3.5/PF fans were in the trenches, fighting harder than anyone, yet 5e snubbed them almost as badly as it did 4e fans, in seeking to woo back the fans of the classic game.)
And, not coincidentally, as someone who fell in love with the classic game, I'm quite fond of 5e. It punches the ol' nostalgia buttons neatly, and, after over a decade of player-focused systems, it's a blast to run D&D with the kind of absolute power DMs enjoyed back in the day - indeed, when I run the 4e campaign I'm finishing out, I find myself increasingly edging it towards the same DMing style.
At the same time, as with every prior edition, I'm not in denial about its technical deficiencies.
Not my position, but it's very like the circular argument common in the edition war. H4ters claim something terrible about 4e (it's mechanics dissociate them, they can't RP, it's an MMO, etc, but when they're pressed to site the actual attributes of 4e that cause those issues, the same qualities are readily found in prior editions that they like. How then can you hate one and defend the other?
There are lots of us - Mearls claimed that the early playtest polls showed the majority of respondents felt this way - who love D&D, and aren't militantly devoted to (nor irrationally hate) a specific edition or era.
Of course, you can decide how credible you find him when he makes statements like that.
The counting squares thing is funny, with the 5' square being a thing in D&D since 2e C&T (c1995), and AD&D using inches that could be 10' or 10 yards, depending.
The ways in which 4e, itself (as opposed to the market weakness and business side fiascos it was afflicted with) was different from prior (and, now, later) editions were clustered around one system quality: balance.
H4ters complained about all sorts of soft qualities that could hide behind the shield of subjectivity, but, when able to cite anything concrete at all, it was virtually always a game element that functioned to provide class or encounter balance, most often the former.
Now, balance is a desirable quality in a any game, but especially so in a complex game with a wide scope, and especially so in a cooperative game where there will be no explicit winner, so being - both of which are likely aspects of an RPG.
That is, desirable unless you're intent on 'winning' a cooperative game by cracking the system, dominating play, or outright ruining the experience for others. D&D had been a very poorly balanced game for a long time, so it's long-time fans had either learned to cope with and compensate for that downside - or to embrace and leverage it. Either way, suddenly playing a much better-balanced version of the same game presented challenges and challenged expectations.
Yeah... no. There's a lot of high-minded retro-nostalgic psuedo-analysis and revisionist history muddying the waters of the classic game, let alone the original game. And the one you cite sounds like it's in that sea of turbidity.
No, early D&D was not intentionally rules for building a shared world. It was rules for dungeon-crawling, wilderness-exploration, treasure-hunting, magic and combat, some of those a lot more detailed than others, the whole of them not in the least consistent in design paradigm.
But, it /is/ true that, if you took them seriously enough, they started to imply things about the world for whom they'd act as de-facto laws of physics. But that's true of any RPG ruleset, even those that go out of their way trying to be 'generic.'
The one example cited by your source, though, level limits, in addition to being an unsuccessful attempt to balance the multi-classing rules over many levels, was a case where Gygax came right out and said he was intentionally trying to evoke the fantasy genre, said genre being humanocentric in spite of featuring super-human races.
Ironically, level-limits were one of the most unpopular and ignored of rules, with 2e raising those limits substantially, and 3e dropping the whole thing entirely (and, you'll notice, it's one thing 5e hasn't brought back).
D&D went about as far as the early 90s. ;P
Seriously, 4e would have been a revolutionary game if it had been published before Over the Edge, for instance. d20, had it been published in the 80s, before open-source was a thing, would have been a solid core system, a worthy rival to Chaosium BRP and GURPS.
Bonds/Flaws & Inspiration is the kind of RP-carrot I recall from early predecessors of modern indie games. Aside from that?
Of course, I'm a grognard in my own way, and am probably much more tuned to the classic-D&Disms of 5e.