Hmm, now I think that the actual difference between us PbtA cultists and D&D cultists is that we make some little change and immediately go "Oh! I'M MAKING A HACK! I'm gonna call it... The Way Forward, sounds cool!" while D&D cultists rewrite half of the book and still maintain that they play D&D.
I think is pretty true, yeah, and if D&D + significant house rules/rules additions/rules changes consistent got referred to as "hacks" and got neat titles like they do with PtbA, it would actually be pretty helpful.
It stems from two very different game histories of course. Early D&D saw "hacks" absolutely on-par with PtbA hacks, and some of them did have different names, like for example Warlock/Caltech D&D, which in like 1976 featured stuff like spell points, Thieves having actual abilities like 4E/5E (rather than just percentile stuff) and some other changes with pretty significant results.
But EGG et al were not impressed by this sort of thing, and really wanted to standardize D&D, whilst still allowing people to have "house rules", so essentially worked against (as I understand it, obviously literally this was before I was born) versions of D&D that were essentially "hacks" to remotely the degree PtbA stuff is (and later, esp. in 2E, against 3PP content at all, which of course changed with 3E). So house rules became isolated and the concept was that each table had their own, rather than there being shared "hacks".
With the rise of the internet and later the OGL for 3.XE you might have expected these to re-appear and they kind of did, but only in pretty limited formats, like the E6 rules, which are essentially a "hack" of 3E (arguably all the d20 stuff was too, but it wasn't presented that way).
Apocalypse World started being hacked pretty much immediately and this worked for AW as to understand most early hacks you needed AW, and so it spawned this very different culture. I feel like the future potentially has more "hacks" of D&D and so on in it though.