In zone blocking schemes it's imperative that the OL get their hands on their defender as soon as possible while moving their feet to establish position. Longer arms allow that to happen more easily, and it gives a bit more cushion for when someone unexpectedly shoots a gap. Nebraska ran zone blocking in the 90s also, but almost every play began with a step forward in run blocking, and that means shorter, stronger guys will do fine with that leverage. With an Outside Zone running play (or any number of other more complicated running concepts in Frost's offense) the O-line's first step is lateral, and they need to be able to pick up defenders on the fly while passing off guys in double-teams in order to climb to the next level. Longer arms mean a longer radius with which to work, and even if a defender shoots a gap, the O-line can still steer him out of the play if he can get his hands on him, and the RB reads the blocks correctly, which is usually not an issue on that play even at the high school level. If this doesn't make sense, let me know, and I can go deeper into it, but I don't want to bore people.