I'm not sure about the salt being drawn in. You can bury a steak in salt, and ultimately it's not going to be that salty. I think it does modify the proteins, making them more conducive to a juicy steak.
The rest I agree with - extracting the water and a dry exterior. If the outside isn't dry, you are wasting a lot of heat steaming off the water before the malliard reaction (browning) starts happening.