and assign all 3pp content to them in the process, sweeping A5e, ToV, etc. completely under the rug
No, not in the slightest. Those products were not made by WotC and are quite fine products.
We all know they created D&D 5e, no one is taking that away by acknowledging that other 5e compatible core books exist now.
And I've never denied that other 5e compatible books exist. But those books were built on top of the 5th edition of Dungeons and Dragons, not "5e that is not DnD"
where does the part in brackets come from?
I see them describe it as ‘A deeper, more flexible enhancement of the 5E ruleset’. What do you think they mean by 5e ruleset?
As to why PF2 and WH40k do not mention 5e, that is simple, they are not compatible with that ruleset, really no surprise there…
The brackets are a replacement, as seen in some quotes when without context it can be confusing to use the pronoun. The line comes from here, though I did not quote it exactly:
Is it still 5th edition, as in is it still the 5th edition of DnD, and in the FAQ for Level Up, Morrus gave an emphatic Yes! Yes! Level Up is still the 5th edition of Dungeons and Dragons.
of course the 5e refers to the 5e in D&D 5e (and now FrogReaver will breathe down my neck again because apparently I use ‘refer’ wrong). The 5e ruleset / platform is not D&D 5e however, it is the 5e SRD.
D&D 5e is one implementation of that ruleset, it was the first one, but it has not been the only one for a while now.
Sure, the 5e SRD is not the entiretly of all WoTC products released for the 5th edition of Dungeons and Dragons, but again, an SRD is a "System Reference Document", it is not a product on its own, it references another product, another entity. And that is the 5th edition of Dungeons and Dragons. And of course the SRD is not the only implementation of the 5th edition DnD ruleset. It wasn't the only implementation of the 5th edition DnD ruleset before it was even written.
But that doesn't make it not DnD.
4e is another version of D&D, so is 3e, ToV and A5e are not other versions of D&D, they are other versions of the 5e ruleset.
"they are other versions of the 5e ruleset." or in other words "they are other versions of the [5th edition of Dungeons and Dragons] ruleset." because that is what 5e means.
no one says you cannot make a connection, the 5e SRD is connected to D&D 5e. That does not mean A5e is the same as D&D 5e or something else that can legally be called a version of D&D. It still is a version of the 5e ruleset however
Of course Level up is not identical to the 5th edition of Dungeons and Dragons, if it was, it would just be a copy of 5e DnD. But again, by saying it is a version of the ruleset, you are literally saying "It still is a version of the [5th Edition of Dungeons and Dragons] ruleset however" Which is my point.