As admin on a site for a software programming language with regards to topic titles and TL-3 being able to change them, it is meaningless. What I mean by that is that I don’t think anyone other than the staff has used that ability. I sometimes wish our TL-3 users would change some titles but they don’t.
With regards to who owns the topic. My view is that the community owns the topic but that the OP sets the tone of the topic. If the topic is drifting away from the tone of what the OP desired then as an admin I will sometimes step in and split some replies off into new topics. Mostly this is either as a request from the OP or a new user not realizing they should have started a new topic.
On a timely note, we have a category for announcements, and when the category was set up it allowed for replies. For one topic the OP really did not want any replies so I moved all of the replies into a new topic. But in talking with some of the other staff it was decided to change the entire category to not allow replies. So in essence when a user selects a certain category they pick up some conditions with that category, in the case of announcements, no replies can be made directly to the announcement. Other post are allowed that can link to the announcement.
HTH