Parity is closer today because of the 85/25 scholarship rules.
50 years ago Bear Bryant was putting athletes on tennis and track scholarships to keep them away from other SEC teams. Bryant has such depth that he didn't have a 1,000 yd rusher until the 70's. It wasn't that they were't talented enough, it was because he had a stable of RBs and kept rotating fresh legs into the game.
50 years ago the SWC was a cesspool of slush funds and extra benefits.
50 years ago there was sharp disparity between the have and have nots.
Don't forget the SEC was segregated during the 60s and you'll notice they weren't playing home/home vs B1G & Pac 8/10/12 teams. When Bama cries about 1966, they fail to acknowledge they played a much weaker schedule than Notre Dame.
Go look at Big Ten teams like Minnesota from the 60s when they were last a title contender (won NC in 1960). Carl Eller, Bobby Bell, Charlie Sanders (all from North Carolina) and others that would stay down south in the SEC today led the Gophers.
Then look at all the NFL HoFers who surprisingly went to Historically Black Colleges b/c they wanted to play in the south and the SEC wouldn't admit them.
Saban has it a lot tougher. Don't be mad b/c Bama doesn't put any restrictions on their program. They let them compete to the fullest within the NCAA bylaws. I remember their years of futility post-Bear and pre-Saban. They were average at best. The right HC can change all that.