[shilala]

Football is acted out like a strategical war metaphor. I think that strategy plays right down the line, tighter and tighter, until anything goes, depending on the circumstances and players involved.
Could a rivalry or game become so intense that a player is directed or takes it upon himself to break someone's knee? Hell yeah. The player will likely feel bad about it later unless he's of James Harrison psycho ilk.
Honestly, I think kids at the high school level are far likelier to hurt someone on purpose than at the NFL level. At the NFL level there's some professional courtesy expressed or implied because there is SO much on the line. While a game-ending injury might be applauded, a career-ender would not. Guys know what kind of hits produce what type of injuries, they're certainly not stupid.
If the bounty thing is dangerous, it's far more dangerous at high school level than in the NFL, for sure.