Seems like the cited studies confirm things we already know: when humans are given tasty high caloric-density foods, they consume more calories than when not given those foods.
I didn't see a cited study showing that these ultra-processed foods led to worse outcomes when caloric intake was held constant. Did I miss something?
No you didn’t miss anything. Everyone is freaking out about “processed” and “chemicals” and ignoring the obvious answer: high calories and low nutrition.
The processed and chemicals may be a proxy for high calories low nutrition, but generally they are used to create hyper palatable foods that are low nutrition. In general, it's quite hard and expensive to produce high palatable foods using real ingredients; food engineering changes that and makes it easy for cheap food to mess with our senses. As far as I can tell, this is the generally accepted argument for the problems with UPFs - they make people want to eat more cheap crap food.