the rankings, just win and you're in, is that it'll play onto the narrative that sec and b1g are better.
If they put 4 sec teams and 4 b1g teams in, and only 1 g6 and 1 ACC and 1 Big 12 and ND, an sec or b1g team is VERY likely to win it all since they have 8 chances and the non sec/b1g only have one each.
They'll point to their champion and go, see? see? We're justified. If you were better you'd have won. Dude, you had 8/12 odds to win instead of 1/12.