Cyclocross puzzle

Sunday, as I was huffing into mile 12 or so of my "really somewhat epic" 18 mile round trip ride, just coming up the hill near the lake, I hear the tinny voice through the megaphone: "...elite men coming up next!" A little further and I see cars with bike racks, flags, and pop up canopies-there's one that says Shimano, is it a fishing tournament? No! It's my first sighting of a "Cross." No, not that; I mean, public property and everything, but it's a race, not a...cross. It's a bunch of guys who look like roadies riding really swell looking bikes-al carbon frames and everything-and I must say, somewhat slowly, around a dirt track meandering along a section of open space within the confines of the lake property, the trail marked by thin wooden stakes with bits of surveyors tape knotted on at the top. Unless I'm wrong, like if the surveyors tape is to frighten birds away, this is what they refer to as a Cyclocross Race. But it doesn't look like much of a race, I mean, they're riding so slow, why is that?
When I was 12-13-14 years of age, all of my friends and I would ride-and I mean ride-everywhere, as fast as our legs would take us. Dirt tracks, sidewalks, homemade jumps, small hills, big hills, we'd ride from the flatlands in town up into Bel Air-and I mean up-down Mulholland Drive and back down Roscomare or Beverly Glen or Sepulveda. We covered a lot of ground in a day, we worked hard at it.
So when, a few decades later, as I'm just trying to keep the E in epic, and I come across these dudes chugging along like Shetland ponies tethered one to another at the carnival, well, it's just not very impressive. Will somebody please tell me what I'm missing? I have respect for anything bicycling that anybody wants to do, don't get me wrong. I just don't get it. Beefing up an otherwise fine road bike-and rider-tossing some mtb stop you now rocks and all brakes on it, along with some knobbies and call it ..what? Slow riding on a road bike in the dirt? Wouldn't you just use a real mountain bike for that? Wouldn't it be faster?