Hmm strong words. Maybe just a different way.
I agree that the content of every single post is strongly connected to the author, though the argument might be given that this is slightly less so if the user hides herself behind a pseudonym.
The edit of a post should in my opinion almost never be done by others (if I focus on good and open content).
My original question though was about the title of the thread. Which ownership we all as contributors share more or less.
I still think that talking about a change should be the best way but I would argue that the position that it belongs to the creator of the first post is very weak at least in the Discourse forums.
I think that really might apply. Furthermore the change is visualized and the first author is informed about it. And can ask the member why he did it.
I think it heavily depends on the goal in the forum.
A case in which a feature is deprecated might give the TL3 users the means to change the title or even simply the admin to archive a thread.