No they don't understand that SO owned the messages: https://news.ycombinator.com/item?id=50287815 - someone telling StackOverflow to "rest in piss" because another user dared edit "MY TEXT" which is "unacceptable".
That person is right to be angry with StackOverflow for that, and another comment explains that StackOverflow was editing their words but still claiming that they them. That can cause reputational damage. StackOverflow should have been sued over that.
Power and responsibility go together. The power to edit needs to be attached to the responsibility of having your name next to those edits. That person's point isn't about ownership at all, it's about attribution.
Presenting CC-BY-SA as "SO owns anything" is an even more terrible lack of understanding.
Your comment is low quality; it's an insult, it explains nothing, and the nitpick changes nothing about the point.