Before that BCS/non-BCS existed for only about 20 years.
Before that Major/Major Independent and Mid Major for about 10-15 years.
Before that it was the newly separated DI-A and DI-AA or FBS/FCS for about 10-15 years.
Before that there were no actual nomenclature similar to today; not even a separation between FBS/FCS and you had current Ivy league schools (at the time independents) winning 30+ national championships.
I'm guessing though you're in your 20's which doesn't completely mean you should paint 100 years of history with only what you know now but it does explain why you do...