There's a difference between me getting AI to write something I want to read, and getting it to write something you want to read. The difference is that I know me, but I don't know you.

The other difference is that, if I get AI to write something for me, I expect something AI-written. If I am writing something for you, you expect something that I wrote, not something that AI wrote.

Moreover, when you wrote it yourself, you are intellectually responsible, you can defend it, while if the LLM wrote it for you, nobody is really responsible: The LLM didn't write it "out of its own motivation", it was merely extrapolating your prompt; and you only provided the prompt, not the extrapolation.

So the intellectual responsibility is diluted to a substantial degree: The text is not the opinion of anyone who can be expected to honestly defend it. It's bullshit in the technical sense.