Why all of the "Thread Closed" messages?

I normally use the "Search Engine Optimization" forum 99% of the time. After the "Phishing" attempt that was discovered here recently. I now watch this thread/forum too. However, alot of these threads have a prominent "thread closed". I was just curious, as I dont see alot of this in the SEO section? I was wondering as to what the reason may be? I am aware of the fact this website is free to use, and its your rules, and I'm not complaining or anything, I just wondered about it...

I guess what made me wonder was this closed thread...
http://forums.digitalpoint.com/showthread.php?t=667479

as I just wanted to comment that I thought it might be a good idea too. I would use the for sale or trade more often, but I too get so tired of all the social network 1 for 1's, or whatever they are called.... Nice site by the way, I've really enjoyed using it recently. I lurked here for 2 years before signing up... Got somewhat tired of a particular moderator at another webmasters forum/website, and started participating here more. Not that I started problems at that website, but he was so harsh in his comments and messages to all the other users that I felt it was time to move on... If you made a comment about a certain SEO idea, you would need a thesis to back it up... However, he could throw out a "one liner" and that was ok too...

 

If the question/problem/complaint/whatever is resolved then it's quite often deemed that the thread has served its purpose and it is locked. If it's not a straightforward issue or there's no mods around to provide an answer then the thread is allowed to run for a while.

Consider this forum as more of a place to ask questions and receive answers rather than enter into discussion.

That thread was probably closed because the same suggestion had been made many times before. The mods must get bored of giving the same answer time after time for threads like that, so it's easier just to kill it dead.