Proofreading is easily done with an editor. I think AI is much more useful for giving critic and advice on how you write your sentences. Setting the tone, refining the main idea, pointing out redundancies are some of the things that I find very useful.
Sometimes, but you have to be careful. IME Claude and (to my surprise) Grok 3 are really good at understanding your style and adapting their suggestions to match. ChatGPT, by contrast, tries to change everything into some kind of corporate drone.