Of course, the salesperson isn't the enemy, and buying from them isn't charity. The transaction happens because it benefits both sides, yet the byzantine maze, lack of information and endless circle is a real barrier to success for both sides.
He's talking about the client-supplier relationship in the context of the client knowing how to buy. It's a great article and especially insightful if you're on the client side and responsible for "buying" stuff, be it products or services.
I completely agree with Seth when he says "Whoever buys the best, wins."