You don’t think people ate carbs 3 times a day in the past? The majority of humans for the majority of recorded history have eaten some kind of bread, rice, potatoes, porridge, or corn with the majority of their meals.
Also in the majority of recorded history being fat was a sign of wealth. I don't think the majority of humans had a surplus of carbs available to overeat them. It's not that carby foods are inherently bad, there's just something bad about the way they fit into modern society, for some people.
