I have no problem with a clean cut block, where a single blocker aims his shoulders at the defender's waist or thigh. If it's done cleanly, then the chances of a defender being injured are no more than a regular block. The San Francisco 49'ers used it all of the time in the Bill Walsh / George Seifert era, and opposing defenders weren't injured at any rate higher than the usual ones.
I do have a problem with Navy, Air Force, etc., where they'll make a blocker engage a defender up high, while another blocker dives at his knees / ankles. Just before the second blocker hits him low, the first blocker releases from the high block, technically making it a cut block instead of a chop block, but it's still as damaging as a chop block.
I've seen it basically end the career of Eric Jones in 1991, whose foot was almost severed from his leg because of a gruesomely shattered ankle. That same game, Bryant Young also ended up with a knee sprain that really slowed him down for several games afterwards, including the Tennessee game where we blew a 31-7 lead, and the Penn State game, where we got manhandled.
It also killed off Joe Schmidt's ability as a decent player. He had below average speed when healthy, and in 2014, when that Navy blocker chopped him at the knee in the manner described above, that turned him into a stick in the mud that even Tommy Rees could probably outrun.