It has though. Those teams suck, but all of them, even the Lions, have put together 11 win seasons or similar within the past ~10 years. The Jets were in consecutive AFCCGs. The Jaguars were there recently. But sustained success in the NFL or NBA is closely tied to having one really good player (QB or whatever 30ppg scorer). And when you get one, it is exceptionally rare that they leave in their 20s because other teams can't really outbid. In baseball, one player isn't taking you anywhere. You have to be able to reload at multiple spots every single year. There is just not an easy way for small teams to do that. There's no way, really, other than drafting incredibly well.