I think it might be a courtesy to those who are into milsurps purely for the collector interest. Much if not most of the activity is related to the CMP matches, builds, accuracy, etc. I think we happen to have a very active pocket of match shooters, so that's driving a lot of traffic.
That said, the post counts are not ridiculous for everything combined. Though I don't have much to add to the collector discussions, I always find them interesting and usually learn something.