Reservations about Reservations in USFS campgrounds

First of all, this wasn't on a weekend nor even on a Thursday. It was for Sunday, Monday and Tuesday. Second, I assume it was a group since the same three days were reserved in all cases. I'm assuming they just wanted to assure a block of time for their get-together even though they knew they weren't going to be there until Monday. From the responses here it sounds as if this is a common custom among some. I still don't like it.