Another possible mechanism that I have heard of are dough conditioners. They make bread soft and fluffy without the need for cultures or letting the bread rise. But bread cultures (such as sourdough starter) feed on the gluten (and make gas bubbles) during natural bread rising. So the gluten doesn't get broken down in "commercial" bread the way it does in "artisan" bread (in quotes because those are two broad categories). So we end up eating lots and lots of gluten in a way that our ancestors didn't.