- It's incessantly (and accurately) argued that referees could feasibly call holding on every single pass play; it's really just a matter of whether or not the ref sees the infraction clearly enough (or whether it happens to be especially egregious). This would end that arbitrary judgment call. Phantom holds and missed holds would no longer matter. Moreover, there would be fewer penalties in general (and as a consequence, fewer stoppages of play).
- If holding were legal, quarterbacks would be able to stand in the pocket much, much longer. But this advantage would be mitigated by the way cornerbacks could now cover wide receivers. The Mel Blount Rule was implemented in 1978 to open up the passing game; essentially, it limits the contact on WRs to one chuck within five yards of the line of scrimmage. But if a defensive back could essentially hand-check a receiver as he runs his route, the ability of that receiver to get separation would drastically decrease. In other words, it would be easier for the quarterback to accurately throw the ball downfield, but much more difficult for any receiver to break open. I suspect the impact on passing statistics would be negligible; the numbers might decrease a little, but that's OK. It's become too easy to throw for 4,000 yards in a season.
- Obviously, concussions can happen at any time. But when do they happen most dramatically? It's usually when a wideout is sprinting unencumbered on a crossing route and a strong safety blows him apart when the ball arrives late. If cornerbacks could keep their hands on a receiver for most of the play, this kind of hyper-violent collision would happen more rarely (because WRs simply could not run free over the middle of the field). Meanwhile, letting offensive linemen hold would also decrease the likelihood of quarterbacks absorbing death blows from unblocked edge blitzers (because linemen could at least reach out and get a hand on the guy as he flies into the backfield). Changing these two rules might be the easiest way to decrease the number (and the severity) of concussions without totally changing the nature of the sport; in fact, it might make the game simultaneously safer and more physical. Football would still look like football.
Still, it strikes me as an interesting idea and not one that contradicts our understanding of what "really" constitutes football or the way football should be played. Of course, even if the game is still football, would it be an enjoyable game to watch if everyone is able to hold or hand-check off the ball.