Art is comprised of two components, the objective craft part (hard work) and the creative talent part (DNA). (Sports works the same way.)
We can all give advice on the craft part because there are only so many ways to go about it and they've all been done. If this was a chair building forum, we'd all have advice on how to cut the wood, shape it, the tools needed, the best glues, the best joints - for every style of chair ever done.
But if someone asks how do I make people want to sit in it, the conversation gets pretty vague pretty fast.
For example, in books we know we want engagement, which means creating empathy. We know we need at minimum an interesting main character, but preferably a likeable one, especially for a series. We can quote Save the Cat, but the actual doing it part within the narrative - the words part - is fairly abstract...
Unless you 'get it' at the creative talent level.
If you don't...writing is going to be a tough row to hoe**.
One example here is Architecture. Schools can teach all of the mechanics and life safety necessary to ensure the building doesn't collapse or kill anyone, but all of the PhD's in the world can't teach creativity. You either live with your head in the clouds imagining 'what if' or you don't.
Books are Art. Some Art is all creative talent, passion without constraints. Generally speaking, this isn't very satisfying. Some Art is all technique, perfect execution, but is also emotionally lacking and therefore unfulfilling.
But when talent meets up with dedication to the craft you get amazing, often iconic Art.
Part of the The Dunning–Kruger effect that gets routinely overlooked is that truly knowledgeable people of specific subjects tend to believe that everyone else understands the subject more or less as well as they do. And, of course, the truth is they don't.
This is why writing advice is so problematic.
I like Chuck Wendig's take on writing advice, of which he gives quite a lot. "All writing advice is bullsh*t anyway, but bullsh*t can sometimes fertilize."
Johan Scalzi is another writer who gives pretty good writing advice. I like his advice too, but, just to illustrate how tricky the subject is - I don't really care for either of their books.
**To reuse the chair analogy, you don't need to reimagine the chair or invent new ways of sitting to make a sh*t ton of money building chairs - or publishing books. You just work on the craft part and do what's already been done. There's a huge market for 'more of the same' Art, from music to painting to movies, tv shows - and books.
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From Harlan Coben:
'Amateurs wait for the muse to arrive; the rest of us just get to work'.
While I agree with the general principle, the problem here is that most writers don't have his talent to push them through. They may understand the craft and mechanics of it all, but coming up with the clever bits that keep readers up all night turning pages can't be found in advice books, degrees or internet forums. I can't say for sure what it is (nature v nurture), but I don't think it can be learned.
Lots of amazing writers don't see themselves as anything special, certainly not Artists. And it's not humility, it's Dunning–Kruger again. I'm, sure Coben truly believes it's just a matter of rolling up your sleeves. It's not.
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On the talent DNA thing, we're drawn to what we like, which often aligns with our natural talents. Good athletes follow that natural talent from an early age, immersing themselves in sport. Musicians spend insane amounts of time with their instruments, painters constantly doodle - because that's who they are, it's not work, it's a love affair. Few amazing writers can remember a time when they didn't write, not to publish, but just for the sake of writing.
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Lastly, sales and "quality" (whatever that means to you personally) are two completely different metrics.
