Here’s a real mystery for you. You’re a worker at a dry dock where you are maintaining a ship. You periodically remove perfectly good parts of the ship and send them away, replacing them with new parts and making falsified records claiming spurious damage that needed to be repaired. At a second facility, the pieces from the original ship are reassembled. Did you steal the ship, or has it been sitting there in drydock all along?
Let's take the more direct approach and move the ship entirely and replace it with a copy.
Have you stolen the ship?
I suppose legally you could argue you haven't. The registration etc still applies to the customers ship, and unless the customer could demonstrate some kind of emotional attachment, there would be no 'loss'.
It's like going to a shop, selecting a tin of beans, when you pay, the cashier swaps it for another tin of beans. Have your beans been stolen?