As someone who frequently answered questions in the 'New' queue, the sheer amount of rule breaking, low effort, and obvious duplicates was astounding. I eventually quit answering questions because 99% of them were not worth interacting with. Just vote close and move on.
Ultimately, I think SO is dead because it got too popular and moderation became untenable.
It's simply not on a new user to understand whatever group interpretation you have made up on top of the written rules. There is no platonic ideal of a good question, the project was doomed from the start if people take that idea seriously. The UX says submit a question about coding while the unwritten rules say submit a flawless peer-reviewed abstract or we close in 3 minutes.
Ironically those 99% asking low effort questions will gain more than everybody who looks at a "high value" question put together. Truly, nobody on SO learned anything writing those questions, they were just regurgitating their phd/previous work. It was grossly performative and I'm glad it's gone.
I'm taking about entirely unreadable posts (not English, or just nonsensical) or posts that were very clearly a copy paste homework question with no code.
I helped hundreds of people of all skill levels for free, simply because I found it enjoyable. I quit when it stopped being enjoyable. It stopped being enjoyable when the quality of question declined to 99% garbage.
StackOverflow was, all too often, not helpful or aligned. It died because the staff were unable to get the moderators to be helpful.