Maybe we should have some spam fighters? Like, fight fire with fire? So whoever created the topic we just have 100 people send them 5-10PMs a day saying "lock your useless thread *link* or the spam to your inbox will continue.
Bad idea. It would be easier for moderators to lock threads, rather than force people to lock them.
In any case, I don't think PMs would bother anybody. Especially if you don't expect serious messages here.