The problem with LLMs is that they write badly. If you want to use a LLM to write, prompt it with what you wrote and ask it to summarize concisely. If it doesn't understand what you meant, you should fix that part and resubmit (to a fresh context.)

The main reason, however, that one shouldn't "write" with LLMs is because it's a waste of everyone's time. If they wanted to know what GPT-5 thinks, they can ask it themselves.

edit:

> The problem is not the use of AI but the people how think they can, arbitrarily, criticize the work from someone else because he used or not AI in the name of “ethics”.

Ah, I didn't realize that the real problem is that people complain about it. If we can figure out a way to make those people shut up, then using LLMs to write for you would be perfectly fine.