I generally don't start many threads because the interwebs are not my only source of conversation. If there are things that I really want to talk about or that I find particularly interesting, I'll bring them up in conversation with friends or family and discuss those things with people I know.
Further, I don't rely upon SpursTalk (or any other message board) as my day's entertainment. If I'm on the computer killing time or, more likely, doing homework, all I'm looking for is a momentary diversion. I'll check in, scan a few threads, respond if something interests or amuses me, and move on if nothing does. I don't feel compelled to extend my SpursTalk experience beyond that. If the boards are dead, or there's nothing happening here beyond obnoxious trolling, or I have nothing to contribute to a particular discussion, there are a million other things I could be doing with my time.