What I don’t get is why it took them decades to figure this out.

Well that’s how it works with just about everything in high-tech capitalism. Enterprise & profits first, downstream and knock-on effects examined later. Just look at plastics, nicotine, pesticides, etc etc.

I also tend to think that sorbitol and other replacements aren’t necessarily terrible in themselves, but look at the way they’re used-- a typical diet drink / food item doesn’t attempt to lower overall sweetness levels, it attempts to replace almost 100% of the sweetness with the artificial product, killing much of the point of doing so.

The good news is that consumers can be trained and untrained over time to crave excess sugars, salt, fat, fried food, etc. So you can reprogram your tastes over time, and get used to vastly lower quantities of unhealthy substances. For example, I used to drink and get normalised upon store-bought iced teas, which contain drastic amounts of sucrose / corn syrup. I just make it myself now, using a single packet of sucralose and a single sugar cube (15 kcals) in about 28fl oz brewed tea (Gatorade bottle). It took time, but it tastes perfectly sweet now, to me.