I have a kid in high school who uses LLMs to get feedback on essays he has written. It will come back with responses like "you failed to give good evidence to support your point that [X]", or "most readers prefer you to include more elaboration on how you changed subject from [Y] to [Z]".
You (and another respondent) both cite the case where someone unthinkingly generates a large swath of text using the LLM, but that's not the only modality for incorporating LLMs into writing. I'm with you both on your examples, fwiw, I just think that only thinking about that way of using LLMs for writing is putting on blinders to the productive ways that they can be used.
It feels to me like people are reacting to the idea that we haven't figured out how to work it into our pedagogy, and that their existence hurts certain ways we've become accustomed to measuring people having learned what we intended them to learn. There's certainly a lot of societal adaptation that should put guardrails around their utility to us, but when I see "They will make us dumb!" it just sets of a contrarian reaction in me.