We only see SG-1 involved when there's a problem. That doesn't say anything about the missions where their help wasn't needed. Presuming that the other teams went on as many missions as SG-1, and there were an increasingly large number of teams, that's a heck of a lot of missions that we know nothing about. There's simply no reason for us to have heard about those missions since they didn't involve SG-1. Of course, they could have taken the first 15 minutes of every episode to debrief us on the actions of other teams, but that would have been less than ideal. It would also not have been all that interesting to watch SG-1 kick back and while other people work.

My point was that not only shouldn't those people be out there, not only shouldn't they be in the SGC, they shouldn't be peeling potatoes at Fort Dix.