In the NFL, the problem has been exacerbated in recent years by the plague of parity. I think I’ve seen more playoff teams with 9-7 records (and worse) in the last 15 years than in my entire lifetime before that.
It got exacerbated by that stupid “everybody gets a turn” rule. I think all of the games that have ended in ties since then both teams got a FG, under the old rules they all would have ended on the first possession.
Parity isn’t really the source of the 9-7 playoff teams, it’s clustering. The league keeps getting at least one division that all sucks, and somebody has to win that division. While I do think winning the division should be the path to the playoffs I wouldn’t mind seeing a 10-6 proviso on that, if you can’t win your division at 10-6 or better you didn’t really win, we’re going to go get a wild card team from one of the divisions that doesn’t suck. There really isn’t as much parity in the NFL as the league wants people to think.