Which industry are you talking about(maybe fang)? The kind of factories making factories and so on in the industry Java code is mind-boggling . And none of it h

Which industry are you talking about(maybe fang)? The kind of factories making factories and so on in the industry Java code is mind-boggling . And none of it has to do with business logic. Asking OOP factory makers to learn about category theory is going to be a difficult task. There are a lot of FP languages that don't require learning category theory. Ocaml has been around for ages and even Microsoft has its own ML flavour mainstream language called F#. Abstraction doesn't seem like the reason to me, it might be inertia.