I think it would help you to use some actual philosophy terms here (apart from the other controversy, which I am ignoring per orange text request.)
Specifically, the useful terms here are haeccity and quiddity. Literally, "haeccity" is "this-ness": the quality or qualities that makes this specific entity itself, and no other entity. Conversely, "quiddity" is "what-ness": the quality or qualities that make a type or category of entities what that type/category is.
So, for example, the quiddity of Socrates is bound up in things like "human", "bipedal", "male", "Greek", etc. These were Socrates' "what-ness" qualities, what kind of thing(s) Socrates was. Conversely, the haeccity of Socrates would be all the things that made him specifically Socrates and no other entity that fits similar categories.
What you call "6e" has moved--slightly--in the direction of primarily focusing on quiddity, and thus slightly away from haeccity. That is, its design leans a little more toward allowing many different specific individual things to be captured in the same overall category, just as "human" captures both Socrates and myself and you and a variety of other entities. Conversely, what you call "5e" places a gentle, but present, emphasis on haeccity; abstract categories are still quite prominent, but (slightly) more attention is paid to the this-ness of each individual expression.
A hypothetical edition that focused exclusively on quiddity would be resolutely abstract, scrupulously avoiding this-ness details as much as possible. Such a game would probably be easier to use, since abstractions necessarily fit many situations, but I doubt it would be fit for purpose as a D&D-like TTRPG, because too many salient details would be lost. But a game that focused exclusively on haeccity would be worse, drifting even further away from being a D&D-like RPG. Further, it would go far beyond the level of tedium and complexity induced by the 3.x model of entity design. (As an example, "class" couldn't exist because that's a what-ness, not a this-ness, so the game would necessarily be pure point-buy--which isn't a bad thing in and of itself, until you realize that now you must design each and every monster you field individually, statting up what is functionally an independent player character for each and every monster you ever field. No repetition--because that would detract from the this-ness of the monster.)
So: a mix of design emphasizing quiddity (abstract categories that can catch many things with one net) and of emphasizing haeccity (individualized, concrete expressions that are X-specific-entity and no other). I would agree that 5.5e (what you call "6e") has shifted slightly toward a focus on quiddity, but "slightly" is doing quite a lot of work there. As in, if the previous balance was, say, 55% haeccity/45% quiddity, it's now the other way around.
I, personally, am quite in favor of such a shift. I think it is much better and more productive to do things this way. Abstraction is necessary to prevent the game from taking eight million years to resolve things, and more importantly, to ensure flexibility so that the system does not break down the moment someone suggests something that isn't already codified on a table or chart somewhere, and to encourage and support creativity that can lend itself to a more engaging experience.
That doesn't mean I'm in favor of sacrificing all rules with an emphasis on haeccity. As stated, I think an insufficient focus on haeccity would be bad for a game aiming at the D&D-alike TTRPG design space. And I understand why many folks want such a deep focus on haeccity: when you know that the game has given individual attention and texture to the vast majority of entities you could encounter (whether or not you do encounter them), that increases the perception that the world is grounded, that the fictional reality has weight and meaning and isn't merely a convenient, and thus hollow, abstraction.
But there is always a price to be paid for emphasis on haeccity--and I find that that price is often one that degrades the experience for those who aren't heavily focused on the design-purpose I call "Groundedness & Simulation". For folks whose only interest is that specific design-purpose, that price is usually (though not quite always) worth it. Unfortunately for such folks, there are other design-purposes for TTRPGs, and only a minority exclusively prefers G&S. Sufficient flexibility to support both G&S and other design-purposes (such as what I call "Conceit & Emulation", or what I call "Values & Issues") is necessary for a D&D-alike TTRPG.
