They didn't have zippers. And, they didn't have elastic fabrics.

I don't think this was a good solution, because it's not common. It was a solution that worked, but perhaps not very well.

A better solution would have been as a corset is made. A corset expands to slip into, and then contracts with laces. That idea could have been adapted to the shoulder area. Alternatively, a seam at the shoulder that could fold over itself a couple of times and is held with buttons.