Why do the two couples have to be "up to" anything? They likely were just enjoying the campground in their own way, just as you were. We'll be spending two nights at a NY state park on our way to our upstate NY cottage following a visit with friends in Maryland next week. I don't expect we'll light any fires either, and may not even spend any time sitting outside. What we will be "up to" part of the time, is visiting our granddaughter that lives a few miles away. Other times, we've stopped at state and national parks for two or three days when traveling just to take a break from the road for awhile. We prefer the usually more spacious sites at state and national parks over the private parks when the locations and availability fit our travel plans.
