There is a way that we can sticky note the topics that may be of long term use to the forum. I do agree with you that there is no reason to respond to topics that are too old, especially topics that were started by a member with a deleted account.
On the other hand, I have enjoyed seeing threads revived and new information added or discussions begun even when the original post was rather old.
As a fairly new member, some of the older posts contain information i find useful, or interesting, though i do agree that some older posts from members seeking advice, introductions, etc can be confusing.
It can be a useful tool, like other have said. You just need to be mindful of how much time you spend on it. It's easy to get sucked in. It is a great way for me to keep in touch with distant friends and family.