When I had started my PhD, I thought the writing part of a paper was just the last thing I needed to do to summarize my results, like a boring epilogue to the more exciting science. What surprised me was how much of the scientific process relied on my ability to convey my ideas to someone else. And to be able to do that you need clarity of mind, you need to have worked through multiple drafts to be able to get to your point as efficiently and clearly as possible. So many times I only discovered what I was actually researching during the writing part.
The problem with AI writing is that it makes people believe that writing is just writing and not a tool for thinking very deeply about the topic you are writing about. I am not completely opposed to AI assisted writing, but if I see AI writing, it’s telling me that the author tried to take a shortcut in their own thinking and it’s a good heuristic that the ideas will not be thought through enough to warrant my complete attention.