I think there is a certain kind of programmer who enjoys the aesthetics of higher-kinded types, and after having made the investment to truly grok them, wants these HKTs to also be useful in practice.
I don’t think the benefit ever materializes and highly abstract code is just indulgence.
Much like the people who endlessly tinker with their IDE/emacs/desktop environment/shell in the name of productivity.
Honestly, they are useful in practice, as long as you’re using a language that supports them properly (I’m not convinced TS is that language). Even without, they constitute a pattern that is very simple to implement which is very powerful.
People believed (and some still do believe) the same thing about generics.
