The whole purpose of server vendors selling blades

is to sell something that has proprietary lock-in on the design, which in turn means less competition and ipso facto,higher margins on the sale for the vendor.

Why do you think that HP was pushing blades so hard? They couldn't make sufficient margin off the rack dense product alone in the face of stiff competition from Dell.

Similarly, IBM is about 40% higher than the Dell or HP equivalent on their blades (your street pricing may vary) because of the perception of IBM as the blade standard and the speed to which the blue adherents signed up for more IBM tin.