OOP is the only way invented so far to deal with complex mutable state. Many practical problems have a lot of that. OS kernels is one example. Right now, Windo

OOP is the only way invented so far to deal with complex mutable state. Many practical problems have a lot of that. OS kernels is one example. Right now, Windows task manager says there’re about 100k opened handles in my system. The state of an opened file handle is huge: user mode buffers, kernel mode structures, encryption, compression, effective permissions, file systems B-trees, flash memory state, and more. Without hiding all that state behind an API, the amount of complexity required to write a byte to a file would be overwhelming. On Linux it’s usually object_do_something(struct tObject *), on Windows it’s DoSomethingWithObject(HOBJECT), it’s 100% OOP, where objects are hiding their state behind methods. GUI is another example. Whether it’s a web page, a rich text document in an editor, or a videogame, the state is very complicated. GUI frameworks don’t compute functions, they respond to events: from user, from OS, and from other parts of the program. All GUI frameworks are OOP, including web frontent ones, e.g. reactjs.org says “Build encapsulated components that manage their own state”, it’s a textbook definition of OOP.