Putting aside the people who need LLMs as a prosthetic, the only writers who are asking AI to write lengthy prose for them are the ones who on that occasion didn't have anything important to say in the first place. Maybe they work a fake job where they're required to do ritualistic writing, similar to the medieval scribes who laboriously copied books by hand over and over again. Now, thanks to AI, they're liberated from having to toil through that lengthy process. So, yes, writing is thinking. It's also willpower. But if the purpose for it didn't matter in the first place, then nothing is actually lost if you stop doing it. You just won't get punished.