If a "trainee" scratches a plate, and it's a plate that we don't see, the watch is still flawed, just that we can't see it. I just don't want something "corrupted" in my movement because if it's not visible through the sapphire case back, I will probably never see it, but it'll still be lurking within. I actually like to have a specific watchmaker in mind before I buy something to ask them if they think the watch is well designed and will be serviced well. Here in USA, Richemont brands generally go to the Richemont technical center in Texas, and THEY can be AWFUL! I've literally seen dozens of watches abused by Richemont Texas and Rolex Texas service center (mostly overpolishing at Rolex). Servicing is very important to me, it can really break my ownership experience.