Yeah - like blocking the plate without the ball = bad, but blocking the plate with the ball = good? That's stupid.
I fully expect the justification is there were too many old school people complaining that blocking the plate is an integral part of the game and it's history and thus they landed on a rule that makes them a little bit pregnant. By only letting you block the plate once you get the ball, it reduces the number of collisions, but doesn't completely eliminate them.
I hate old school BS like this.