Anyone who posts to a thread validates and supports it.

I know what you mean, and agree with it a lot of the way. But there can be a trap of imagining that a thread has an existence over and above the posts that it is made up of, and that whatever the intent of someone who started it might be has some special significance.

If a thread has developed into a pointless row about nothing in particular, leaving it be is often the sensible thing to do. But other times an interesting and relevant discussion is developing, albeit maybe interspersed with ill-tempered coat-trailing and personal abuse from people trying to stir things up, and I don't think that the stirrers should be given the privilege of shutting down the discussion. (And that's not a comment pointing at anybody. I feel it prudent to emphasize that, because sometimes people can be a bit thin-skinned here on the Mudcat, or something you've said with one meaning can take on a new one you hadn't meant, because of an intervening post etc.)