At what point do you draw the line on something like that? I could say the same thing about Travis Morin and the logic would still hold up. I highly doubt all those teams would take a complete unknown commodity over a freak talent like McDavid in the hopes that he'd step right into a top 6 role with a cup contending team. We have no idea how Kuz would perform in the NHL, he might be an instant top 6 asset or he could find himself a frequent pressbox visitor.
If we're only talking about best players (ignoring young studs who aren't ready to play against men) outside the NHL I'd say Kovalchuck owns that distinction by a large margin.