> they know from a long way away what watch brand is on that guy's wrist
No, they didn’t. The makers of movements and makers of cases were separate. From far away you only know the case on the wrist. Not the movement. (I think Rolex was the first mass-market Swiss watch brand to vertically integrate. Patek may have been the first boutique.)
They were. The Acquired podcast on Rolex really opened my eyes to this whole world. They defined the playbook in the 1930s that Apple repeated in the 80s and especially 2000s.
The movement isn't part of the brand. It's not part of the signal. The case/dial/sometimes band are the brand. And if you couldn't tell them apart, they wouldn't be any good at signaling, the entire point of wearing them.