Alot of the generic interfaces you design in OOP end up being useless. Never re-used and pointless. You never needed to make these interfaces in the first place
In category theory, you will be able to create and identify interfaces that are universal, general and widely used throughout your code. Category theory allows you to organize your code efficiently via interfaces and thus enable Maximum reuse of logic.
When creating an interface you largely use your gut. Category theory allows you to draw from established interfaces that are more fundamental. Basically class types in haskell.
If you want to see the benefit of category theory, you really need to use haskell. Monads for example are a pattern from category theory.
Also a lot of what people are talking about in this thread is exactly what I'm saying^^. I'm just saying it in less complicated jargon.