IMNSHO a thread has an original poster, who may have had an original question, and who is free to redirect to that question when the thread drifts. However, the thread does not "belong" to anyone, and being rude about redirection, well, is rude.

It's kinda like a gift - you can't really control what people do with it, but unlike a gift, you can at least ask them what they're doing with it...

A little more like a child - you can rear one as best you can but then they do grow up and take on a life of their own. But as their parent, you do have the right to attempt to redirect them.

Wait, is this a projective test?

Are they all? Threads, I mean?