If linebackers did not wear helmets, they would not block with their heads. Helmets were designed to prevent serious immediate injury like skull fracture. A helmet was not meant for head-on collision, and a mortgage was never intended to back a security.
Head injury is an occupational hazard for football players the way getting sued is for attorneys. While criticism about concussions resounds from too much head in the game, criticism of mortgage-backed securities arises from not enough skin in the game.
Banks sold risk and the risk kept being divided and resold until risk was so diluted the banks became cavalier at levels to equal the greed of investors. Banks had very little skin in the game, which left a lot of people shirtless.
Football is not about to go away. Neither is mortgage lending, despite its difficulties. Risk analysis is running high in both arenas with long-term considerations a major proponent of discussions. Lenders are undergoing massive changes in regulation, and there is a recommendation to disallow NFL linemen to go into a three-point stance before the play to prevent players from springing head-on into the game.