Why close threads?

[aysiu]

If a thread starts off legitimate and gets hijacked by people who want to personally attack each other, why lock the entire thread? Having been a moderator myself, I know you can easily mark the offending posts and move them to the Jail or just move the entire thread to the Backyard.

Can someone explain the reasoning behind locking this thread (http://www.ubuntuforums.org/showthread.php?t=120582), especially since someone posted something substantive within an hour of it being closed?

[KiwiNZ]

Aysiu The thread in question was leading nowhere. It was,despite warnings fostering a lot of bad behaviour.
The type of post that were being made can as you know from your moderator experience spread to the rest of the forum and we experience a marked decline in post standard.

[aysiu]

Can I assume that you're discussing a temp ban on certain members? There were a lot of personal attacks in there.

In any case, you're right--the point was made. The thread wasn't going anywhere after that. Case closed.