I believe that other staff members might just join this conversation soon.
At times, the thread itself isn't the problem, but the content within is. There can be a mature thread, but in that thread, other members spam and flame. Sometimes it will just be too much effort to deal with everything individually, so at times the entire thread is closed or trashed.
I don't just delete threads I dislike, there are quite a few threads I dislike, yet at this moment they're still open and going. For example, all those threads about the staff, I deleted a majority of them because they were basically spam, opinions are welcome, but in a mature way. An example is the "numbers" guy, I deleted the same thread about five times, it was time for him to go, which is why he's now banned.
If there's a need for more mods, then the admins will add more. That's if there are enough mature members that can handle responsibility without breaking though.