Okay, not to protect their "paid" jobs, but to stay active on the volunteer committees (job). If they didn't keep adding things (and for a variety of reasons and motivations), the committee would be looked at as not doing anything. A committee not doing anything will be dropped or the members replaced. I've been there, done that, and know the routine. Those meetings are fun to attend, get to do some in-depth thinking, being creative (look out here), and get into some good, heated debate. Who can we protect today?
I don't mean to imply that the committees are wrong, just the nature of the beast.