> I wouldn't say reuse of functionality is a core aspect of OO
You'll find it in practically every object-oriented language, starting with Simula. Later Smalltalk, Actors, CLOS, C++, Self, Java, Objective-C, Python, JavaScript, ...
> making things "reusable" only to never be reused.
It's similar mind-numbing how much has been reused.
Yes, there are a bunch of frameworks, which make use of inheritance and/or delegation.
Flavors (an early object-oriented system for Lisp, early 80s) provided multiple-inheritance, mixins, method combinations, etc. and a bunch of software made use of its features. Object Lisp was another OO system for Lisp, which one used for example in an interface builder, which made extensive use of delegation. The Common Lisp Object System later was designed improving on Flavors and LOOPS (from Xerox), switching away from message passing, adding multiple dispatch. Thus dispatch based on inheritance works over possibly multiple arguments.
Inheritance and delegation have a long history in Lisp going back to the 70s.
You'll find it in practically every object-oriented language, starting with Simula. Later Smalltalk, Actors, CLOS, C++, Self, Java, Objective-C, Python, JavaScript, ...
> making things "reusable" only to never be reused.
It's similar mind-numbing how much has been reused.