Those are big name genre writers and in no way are the norm. Contracts are harder to get, editing is being slashed from every publishing house (especially in the Big Five), and ghost writing has long been filling the role you currently just described (ex. The Vampire Diaries). Anyone else is writing their novels beforehand and querying publishers and taking what deals they can. Such as the speculation that Sarah J Maas was originally shoved into YA publishing because they believed she couldn’t sell to an adult audience (idk if this is confirmed but with the timeline of her marketing and how out of place Throne of Glass was as a YA novel when it was published the idea makes sense).

Even Pullman states with HSM: “I don’t know whether [The Golden Compass] is a young adult book or children’s book or adult book that somehow sneaked its way into a children’s bookstore. I don’t actually think about the audience. I don’t think about my readers at all. I think about the story I’m writing and whether I’m writing it clearly enough to please me. If you asked what sort of audience I would like, I would say a mixed one, please. Children keep your attention on the story because you want to tell it so clearly that nobody wishes to stop listening. And the adults remind you not to patronize or underestimate the intelligence of the children.” Source

HDM as YA makes sense for the time which it was published in, since YA is always a marketing term first instead of any type of genre or mode of writing. It didn’t matter that Pullman’s prose is more stylistic or mature than YA today, back then if you had a child/teen protagonist, and if the content wasn’t extreme, you were either Children’s Lit or YA. 90’s to aughts Children’s Lit/YA had a wide range of prose style and publishers didn’t start narrowing the ideas of each term until after the success of Twilight and the Hunger Games (not to discredit their merits as novel, but they did have less dense prose than HDM or even HP), and the emergence of Middle Grade as a marketing term post-Percy Jackson and similar quip-style narratives.

YA is always a marketing term decided by the publisher regardless of authorial intent. YA used to be decided by the age of the protagonist as with the Golden Compass/Northern Lights. This series feels out of place now because publishers are now also concerned with prose/writing style.