I think using AI for brainstorming can supplement other ways of gathering ideas and facts for writing. But AI, in my opinion, cannot replace the human brain and human creativity. For this reason, I believe AI will work out best for very experienced writers who have walked the long and slow way of learning to write over many years and tens of thousands of hours of practice.
As a former writing teacher for decades, I somehow am happy that I don't have to face the challenges of examining students' texts where big parts are AI-generated. But at the same time, I regret not anymore being a writing teacher who can explore the benefits of AI tools together with my students.