Why are people so gung ho about not posting on old threads?

I think Colibri’s take is a valid one, leaving the thread open in case someone might usefully contribute. Ideally no one would necropost shlock or such shlock would get removed, but whether a zombie adds usefulness is sometimes subjective and can often result in an irritating barrage of comments coming after it that only point OUT the age of the thread. Perhaps a good set of rules to follow for all forums should be:

1.) Don’t post on old threads unless you really have something useful to contribute, and a mod deletes those comments that aren’t useful
2.) Don’t comment on how old a thread is that was resurrected, because it accomplishes nothing, and a mod deletes those comments, because they aren’t useful
3.) Never lock a thread.

Just my take on it. While I’m dreaming, I’d also like a trip to Bermuda.