I think normalization is the problem but not because people didn't drink sweet things; my suspicion is that previously they were drunk rarely and in smaller quantities (due to cost, if nothing else).

We've gone from "Twelve full ounces, that's a lot" to a 12oz can being the smallest commonly available size, and a 20oz bottle being common in vending machines.

Over my lifetime, the "medium" size soda at a fast-food restaurant has roughly doubled.