Madman, I fail to see how you reached the conclusion that there would be zero forward motion of the aircraft. The scenario says that the conveyor matches the speed of the plane, not the speed of the wheels. If the plane goes nowhere, the conveyor doesn't even turn. If the plane starts moving forward, the conveyor does start to turn but affects only the wheels. The plane is already moving, and is pushing air, not the surface.

Rinky, an aircraft taxis by pushing air, there is no drivetrain connected to the wheels, just steering at the nose wheel. The wheels are just there as an alternative to scraping the belly of the plane everywhere.

Madman again- the cats on a carrier are fairly irrelevant to the other discussion, but essentially they are a thrust enhancer. Perhaps the Navy could come up with a way to make jets take off of ships using thrust only, but the steam cats are fairly economical and very effective.