You can't swim to shore in 45 degree water. Your muscles shut down. You're dead -- unless someone pulls you to safety.
I dont disagree with you at all. I am just saying you can fall off a boat 20 feet from shore and swim in or at least have a fighting chance. I know the odds are bad. To NOT be able to swim and be in water over your head is just a death sentence should something happen.
Cold water aside, if you are in a canoe in deep water, and you cant swim and do not wear a pfd it is foolish beyond words.