i have seen them locked because they were in the wrong "thread/topic title", it came with an explaination as to why,and where to post that info or thread. no biggy.

there are different reasons..

One reason some threads are locked is because the person who started it asked for the moderator to lock it. It's happened in the past when someone posts about an event going on in their life, usually a sad event. Then comes the time when that person wants to move on and doesn't want any more comments made on the topic. Just another reason to lock a topic.