Why do most makers of AIO water cooling not show the contact surface in their marketing material? Isn't that more important than any of the other things, except maybe the pump?

Been using an Enermax Liqmax 2 AIO cooler with 240 mm radiator for a year now...no complaints from me ..it does the job of cooling my Ryzen 7 1700 ...i use my own fans on the radiator ( 4 x 120mm Noctuas ), in a push - pull orientation.