so you're basing your statement on personal, anecdotal observation. personally, I've seen kids get hurt playing all-out. it doesn't make sense to me that not pressing, walking the ball up in transition, playing a soft zone with no ball denial on the perimeter, not following your shot, not contesting a rebound that's 60/40 to your opponent, not going for the steal--any of those things--makes your team more vulnerable to injury.
a coach on the better team faces a tough choice. to continue to have your team "groove" good habits that can make a difference in a close game, and humiliate your opponent, or to slack off, possibly open the door to bad habits, but exhibit (and model) compassion toward an overmatched opponent. the choice is not obvious either way, but I don't think injury risk is a factor.
paradoxically, a really elite team (most likely to inflict a blowout) has the most incentive to maximize every game minute for it's possible minute advantage down the road against an elite opponent.