The problem with procgen for variety is that it's almost always a few procedural changes layered onto a finite, typically small, set of "types". You can see this in games like No Man's Sky, where there are technically billions of different animals that you might encounter on a planet, but a lot of them are pretty similar. Even in DRG with their terrain gen, they're building on room templates that you'll start to recognize the more you play.

It's kind of like those ad campaigns about how many millions of ways you can make a burger. Sure, a 1/4 lb cheeseburger with lettuce, tomato, onions, and ketchup on a sesame seed bun is technically different from a 1/4 lb cheeseburger with lettuce, tomato, onions, and mustard on a sesame seed bun, but they're both still burgers. You might hit onto some unique combinations (e.g. meat, cheese, and toast on the bottom, with no top bun -> patty melt) but you're ultimately still just seeing burgers everywhere, and the system that generated the burger isn't ever going to generate aloo gobi.

It's pretty good, agreed, but we've had procedural generation since before minecraft. It doesn't have anything to do with ML/AI afaik.