The "writing part" is not neatly separable from the "ideas part," much as AI-writing defenders would like to pretend so.
And for the record, you can have a lengthy conversation with an AI to communicate your ideas and then use the AI to draft the message. It'll have AI tells in it, but so what?
"That's literally just the output from a random word picker."
"Don't engage with the mechanism of production! Engage with the content! If it's bad, explain how it's bad! Not everyone believes the output of a random word picker is automatically bad!"