This is probably not the place to discuss just how fragile IRL feudalism was to actual runs of bad winters and sub-par summers, which were notorious for causing famines that spread across nations. I can’t speak about how it works in Westros, but volcanic winters and bad solar weather shifted the tides of history here on earth.

Considering the notion of decades long winters, the people of Westros would likely be forced to be migratory much like the Dothraki.

That all said, it still was a rich world, and I suspect Martin just wrote himself into a bunch of corners.