You can double up on a lot in high school (AP, IB, dual enrollment) or CLEP out of a good number of GenEd classes, but not everybody has the access and support they need to pull that off. There's potential value in going to college (as in _being in college_) that isn't strictly measured in credit hours as well.
Oh absolutely, most of the value is being there not in the credit hours. At Cambridge Uni you can't just condense the time for a BA, no matter how brilliant you are. You spend time 3y on learning. If you're fast, you just learn more.
