I think the big difference is that on Silversea you only need your keycard to open the door to your suite and check off and on the ship, rather than having to use it multiple times per day to charge something to your cabin.
I was very happy to have the phone on a lanyard with a pocket for the keycard, especially when I discovered that I didn't need to pull it out to use it; I could just put the phone next to the sensor pad. Except for my reading glasses, it was generally all I carried around with me, except for my cane when the seas got rough.