Oh, cause I thought you know atleast one of them would actually be watching the play. You're right though, it was totally behind the play. 
My point is simply that if something were to happen behind the play, then everyone would be bitching about the fact that they should have seen it. Other things are going on, and if this happens in 100 games, I bet 98 times it will be caught. It was missed this time, and as long as human beings are reffing the games, things are going to be missed.
Umm, yes I managed to grasp that complex concept.
You do understand that one of the most important things going on in the game that the two referees should be watching is the guy carrying the puck up ice?
I guess Couture could've sidestepped the whole issue by just tackling Stoll, since apparently both referees were watching those other things going on that were way more important than a Kings player trying to carry the puck into the offensive zone on a power play.
Its a complex concept that many people, who are critical of the refs, don't understand because they have never reffed a game in their lives.
There are many important things going on in the game, and you are correct the puck carrier is one of those, but at the same time my point still stands. One ref could have been watching what was going on behind the play while the forward ref could have taken his eye off the play for a second. This kind of thing happens every now and again. Is it excusable? No. Does it happen? Yes. So long as they don't change the way games are reffed, the system will continue to miss things.
Which is why when some of these alternate reffing systems were introduced, I was very encouraged. Having an off ice official that had an elevated platform to watch the games and catch more infractions was a great idea.