Then what is the point in docking at all? Now you have to keep track of what's on the dock and what's on the phone. Plus, by the time you integrate all this into a dock, you basically have something that costs as much as an inexpensive PC, so why bother?
You'll need something to connect all those dock components together so you don't have to run several cables to the phone. Something like a motherboard. So you'll have a full computer sans a cpu.
(And the GPU, and maybe even more RAM etc).