Maybe I'm getting too jaded but I'm struggling to be quite that charitable.

The entireity of the human-written text in that comment was "From ChatGPT:" and it was formatted as though it was a slam-dunk "you're wrong, the computer says so" (imagine it was "From Wikipedia" followed by a quote disagreeing with you instead).

I'm sure some people do what you describe but then I would expect at least a little bit more explanation as to why they felt the need to paste a paragraph of LLM output into their comment. (While I would still disagree that it is in any way valuable, I would at least understand a bit about what they are trying to communicate.)