The motors are not just motors, they just happen to be motors right now. I think it is the selfish gene that describes the path from a protein structure that facilitates the movement of molecules across the cell's membrane into a motor with a flagellum attached.

These things that are claimed to fall apart when a single step is removed were not there from the ground up to provide that specific function, separately they would have provided different functions and when they fell together in a certain way provided a huge benefit. The little bones in our ears were a part of our skulls before they were requisitioned by the ear.

The issue seems to be that the argument looks at how things are and assumes that it was the only thing that these parts have ever been working towards. That any steps in between were useless until put together in this way. Where it is more accurately a bunch of different things coming together to perform all these different functions.