Because I thought it might be useful to prevent someone replying to a node that's several years old.
in reply to Re^2: Do we ever want to freeze threads?
in thread Do we ever want to freeze threads?
There's nothing wrong with replying to a node that's several years old. Why is a discussion over hashes from two years ago no longer valid today?
That's because it's very unlikely that anyone's going to see it, and in any case it's probably in the wrong place.
Of course someone will see it. Discussions are valuable beyond any supposed expiration date. Many people use Search (or even Google) to find very useful old discussions on Perlmonks that help them with current situations. Any contributions made to such threads from the date of creation onward are of value - including the contributions of the person who found it useful.
This isn't Slashdot. Discussions here are valid without end. There is no reason, in 2005, to be discussing how unfair it is that Kevin Mitnick is still being held in prison in an article posted to Slashdot in 2001. However, an in-depth discussion on map/join from 2003 is certainly worthwhile today. That is the major difference.