Matthews led with the crown of his helmet, in the QB head area, and in that situation, that's going to rightly draw a roughing call. It was the right call. Boo hoo. And all the other excellent points made in this thread.
Also, re: officiating, on the Rams non-TD call on that pass, called out of bounds, the idiot announcers never commented that the ball MOVED in the receiver's arms between the time it could have been a catch and after he was out of bounds, in other words, the Rams receiver lost possession and then regained full possession only after being out of bounds.
All in all, the game was decided by players making and not making plays, down to the last missed FG. Even on FGs, Zuerlein had one earlier in the game that snuck inside the post, while Myers had a similar miss just outside the post. Basically it all evened out.