Part of the problem is that they can sometimes read as...
I have a problem, I really need help/advice
200 posts of kind, thoughtful, useful advice
3 years later somebody resurrects it and says I have a similar problem but it's different in a very key and pertinent way. What shall I do?
People respond to the op. People pick up on what other people said on the first page. Nobody is actually helping the new pseudo-op
Finally somebody posts it's a zombie thread.
People still answer the op
It's a massive waste of time and helps nobody. You also get zombie threads resurrected because people are being goady or advertising or being disingenuous or trolling.
Accidental zombie thread creation is one thing but sometimes it's at best irritating, at worst designed to mislead.