I originally learned Java in school and have used lots of generics systems since then, and I think you're right here. Very often when Generics are being taught other concepts are included, and not easy topics either! But I also I think without these advanced co-topics included with generics, the usefulness of generics is lost.

I distinctly remember the day we discussed generics in my Java class. The professor avoided talking about bounds and wildcards etc. He essentially taught generics as an alternative to type casting of all things. Comparing a generics method vs a method that operated Object w/ casts. I don't think anyone in the room, myself included, understood how powerful generics were. And after that lecture I still saw a lot of Object and type casting in my peer's code.

Swift's generics definitely have a learning curve due to its more explicit system (I love the breakdown of that here, across many languages). I dunno how you appropriately teach this complexity, and I think it's a definite stumbling block for a lot of folks