It used to be that pushing a runner from the back was illegal. Now it is done all the time. It sometimes looks like a rugby game out there imho. I think it should not be allowed on a QB sneak and on a running play, forward progress should be called when another offensive player starts to push the pile forward. Anybody like it when they start scrumming out there?
The rule has been around since 2006, but I think it's an interesting risk/reward scenario. I personally wouldn't want a 380lb lineman (or multiples) throwing their body at my franchise QB back/legs/tripping and landing on an ankle or planted foot while the rest of the team on the other side is doing the same.
My guess is we will likely see more scrums in the near future that have big old backup players/fullbacks or tight ends in there to get smashed for 6 pts. Im ok with that, just not with a 50million dollar QB or starting RB.
To me, it's like seeing your #1 WR fielding punts... It's just bound to end up poorly at some point and risks unnecessary injury to a key player.