Some strange assumptions here....

Brit doubles, and the better 'continental' offerings, were traditionally built to the correct weight for comfortable recoil management and muzzle control when close to DG. The idea that a lighter-weight gun could not have been built a hundred years ago because of material strength limitations is simply incorrect.

The truth is that makers at the time knew what the customer wanted/needed in a time when most DRs were hunted on foot against DG on a daily or weekly basis. The artificial PH-backed one-shot safari of today might permit a light-weight double-rifle shooter to happily survive his encounter with DG, but a light-weight heavy calibre DR would have gotten you killed sooner or later during the 'heyday' of African and Indian hunting.