I personally don't use an LLM to spellcheck (browser spellcheck works fine), but I see no problem with someone using an LLM to point out spelling errors.
And while I don't complain about others' spelling errors, I sure do notice them. And if someone writes a long wall of text as one giant paragraph that has lots of spelling/grammatical issues, chances are very high I won't read it.
Some people write very poorly by almost any standard. If an LLM helps the person write better, I'm all for it. There's a world of a difference between copy/pasting from the LLM and asking it for feedback.