How can Sklansky-Chubukov rankings help me?

[scarr]

I have really enjoyed No Limit Hold'em Theory and Practice but I don't see how the S-C numbers can help me.

The critical point in the equation, is whether or not a perfect player will fold or call your all-in if he knows your hand.

This number is based on two assumptions which are not valid at the poker table: 1) your opponent is playing perfectly, and 2) your opponent knows your cards.

How can a number based on these two assumptions allow you to make a better decision than just how well a hand will do against a random hand after all five cards are dealt.

If I want to know what chance an opponent has of folding, I would look at his stack, my stack, where we are relative to the money, and how loose/tight he is. I am not going to show him my hand and hope he plays pefectly.

So how can a number based so much on two incorrect assumptions help me?