If it is already, my bad.

But to my knowledge, the ESRB ranks a game only by watching clips and basing it on violence, language, ect, but difficulty isn't in consideration. 

I know Ocarina of Time was rated E, but I couldn't get past the Deku Tree until I was 10 (I'm not the smartest kid, but still). It would be terrible for a kid to try to play an "E" rated game to find that he can't even fathom mastering the controls.

So am I onto something? Is there something else I should consider? Am I way off? Thoughts?

Well... ESRB is rating content that may corrupt you :P

Difficulty isn't going to give a kid any ideas or anything. They're just not going to beat it. I did that when I was little and beat nothing but still had fun.

Nope, honestly difficult is so overrated these days. Back in my days even games like this one or this one could beat you, kids have things so easy these days.

naaaaaaaaaaaaaaaaaaaaa, ESRB is fine the way it is.

But then Magician Lord would be banned from sale forever...

If they messured how hard a game was almost everything now a days would be 5 and up

I think it should have a little bit of weight in reviews but thats it.

If that was the case "I wanna be the guy" would be rated N for never fucking play.

the ESRB (or any other similar institution) has no business rating that kind of thing, there is nothing stopping publishers putting their own age recommendation on the box tho. Not that age really has much impact on gaming skill, I know 10 year olds that can beat the pants off me in some games, ofcorse they generally get 1 maybe 2 games a year so they are generally practiced lol.