Playing too many cupcakes too early doesn't give you a good measuring stick of what you've actually got. Those games are damned if you do, damned if you don't types in that if you win by 4 TDs, ho hum, you're supposed to. If it's a nail biter or you lose, the season's over, the team sucks, the staff sucks. Can't win either way.
Certainly does NOT prepare you to go toe to toe with a team with comparable talent and physicality. The big boys play just a bit faster and rougher than FCS and MAC. They have a few good players (who'll get snatched up in the portal) but not nearly enough, many times, to make the game competitive.