Take one example. Jeff VanderMeer. He openly rails against H.P. Lovecraft and yet Jeff's breakout novel (Annihilation) is a very thinly-veiled retelling of one of Lovecraft's stories (Colour Out of Space).
I mean, it's a vastly better-written, more human, more humane and even more intelligent book that Lovecraft could
ever have written, on his very best day. So I'm not sure exactly what you're going for here, but it looks like you're swimming out to sea past a bunch of signs about sharks and undertow!
Take one example. Jeff again. Jeff and his wife, Ann, are editors and anthologists who cover a wide range of topics, including sci-fi...and yet the best definition they could come up with for what sci-fi is happens to be...wait for it..."it happens in the future." Which is the single dumbest definition for sci-fi it's possible to give. It's such a stupid definition that anyone who's read more than five short stories or two novels in the genre would be able to spot just how terrible that definition is.
And what you're pointing to here is just a common phenomenon across multiple genres and even into literary fiction!
Load of highly intelligent and skilled authors are not actually that as critics or descriptors of genre. All you're proving is, ironically, critics are probably a necessary evil, and a great writer is not necessarily a great critic, and it's fine that vice-versa is also true.
Sometimes you get both in one, but very often not!
Michael Moorcock vociferously hated all of Tolkien's work, particularly LotR, yet a lot of his work is to some extent a reaction to Tolkien's work. And that's what I would suggest is the case with Annihilation - he saw something done wrong, and wanted to do it, in his opinion (and I agree in this case), right. To do the same sort of general idea more justice.
If I talk to my sister she could remind of various literary fiction authors with similar issues - where they're brilliant writers, but terrible critics, some of them downright incoherent when they're not writing a book (just read some interviews with Booker prize winners, good god). Oh my god I can almost remember a bunch of the truly insane things various genuinely good literary fiction authors have said.
Also if you're suggesting people shouldn't critique Lovecraft the only possible response is "LOLZ", or perhaps, "It's 2023 mate".
EDIT - Hell, you want the ultimate in "Really?! REALLY?!" technology when it comes to authors, look no further than young JK Rowling, decades before she became an obnoxious TERF. She made the following claims:
1) No-one had ever written a novel about a magic school before.
No she didn't qualify that, in fact, what she actually said kind of implied no-one had ever written a book about a boarding school before, per se (but that was less clear). Not only was this not true, but there was actually-popular British series that she'd probably either read growing up, or to her own kids - The Worst Witch. And books about boarding schools are an absolute standard in British fiction.
2) That Harry Potter wasn't fantasy, and also fantasy was just for teenage boys and people who thought like teenage boys.
Again very clear on this. HP was not a fantasy novel, and those were only for teenage boys (I believe she might have said thirteen year old boys specifically). Completely dismissive towards the ENTIRE GENRE. I remember in the interview I read (which was in some fairly mainstream magazine), it was clear even the interviewer was shocked by this response.
Now, I will say, a few years later, she changed her tune, but only after she'd realized that fantasy fans are absolute simps for book serieses.
Argh I can't remember the third stunner, maybe I will later.
