I agree with @PandaPlub , this would be nice. I do understand that it can be abused, but I think it got more positive than negative sides.
As @hgbf said there are more pros than cons. And it is the user's choice, sometimes the creator of the thread would request a lock from a helper and the helper would have to do it, now you can do it yourself, which saves time and effort ps: maybe there can be a message limit, like 30 messages required to lock thread@PandaPlub threads are closed when a mod or helper or admin give the answer to the thread so why give the powr