I've written a lot in my life so far, including books and novels, and never used AI for it. I don't see the parallel. If you were right and it was the same as plagiarizing, then the use of AI should be prohibited entirely. However, to me it appears more akin to using tools like spell checkers, CAS pocket calculators, and Grammarly. It's another tool. I don't really get the fuzz people make about AI. I'm also fond of judging the content of texts regardless of the author. Has that idea come so much out of fashion?
Because plagiarization is not illegal. It’s just unethical and dishonest, and in certain contexts where your work is directly related to your status or compensation, it gets you in trouble. Copyright violation is a specific type of plagiarism that is illegal, but LLM output is not and, in current legal understanding, can not be copyrighted.
Using the services of a human editor is not plagiarism, and mere editing is not considered coauthorship. Mentioning or thanking the editor is just a courtesy, or a contractual obligation at most. LLMs don’t need thanks so most people probably agree it’s fine not to mention it in a casual blog post if its part really is just editorial, brainstorming aid, or similar. (But context-specific terms and conditions apply, obviously.)
What is absolutely not editorial use is making a hundred-word prompt and asking an LLM to expand it to a thousand-word blog post, or a thousand-line computer program, just like it wouldn’t be to ask or pay another human to do it for you. At most you’re then a coauthor of the LLM. This should be obvious, really, we have literally hundreds of years of history on the ethics and norms of assigning authorship on creative works. LLMs should change very little of that.
And then there’s the quality issue. If there were a human author that ghost-wrote blog posts or program code for people, and their output would always have the same known quality and accuracy issues, I’d want to be warned rather than having to spend time on figuring it out every time. Reputation matters.