Again, if you think the artists don't use AI, it's because they didn't tell you.
A good example here is "I'm stuck, what rimes with x" that is a stereotypical writer block for song writers. Do you know what easily solves that problem?
LLM trained for it. I.e. Suno.ai.
Song writers writing a specific tune that just doesn't sound right that want to iterate on several close variants to determine what would sound better. Do you know what does this quickly? Suno.ai.
Again, the artists probably could, as we say it here, "climb up the tree ass first" and do this themselves. It will take them thousands to tens of thousands of times longer to solve the problem at hand than AI would solve it. But they could do it by hand.
But successful people are always starved for time. So they take every tool that will let them have a significant amount of extra time. AI is currently by far the most important tool in this category.