Nebraska used to have so many advantages that other programs didn't. Their S&C was well above others, they could get players who they can not now, mostly because the days of players showing up on campus and not going to any classes does not exist. There are still easy avenues for players to do more football than class, but they can do that closer to home and I would say most major programs have passed or matched NU in facilities and certainly coaching. There's not a lot of reasons to venture that far north into the middle of nowhere anymore. It used to be players would have problems getting into southern Cal schools or Florida schools and Texas schools, just go to Nebraska then. Landscape has changed and not for the better if you're Nebraska.
They had a walk-on program which really meant you weren't a walk-on, you were just getting your free ride differently than you would on scholarship. 0.00 gpa, they'd get you in. Criminal background, come to the land of corn, we'll tell everyone you are reformed. It wasn't just NU, the Big 8 had a thing going and for whatever reason ou was the only one to come out ahead.