People disagree widely on what OOP really is/means. I've read and been in many definition debates. Even defining what inheritance, polymorphism, and encapsulation is, is also a can of worms.
That's just one person's model. It may be an interesting model, but it's not necessarily "true" in the sense of acceptance. Type theory is also a model, not a definition. It's useful in the practical sense, but that doesn't necessarily mean it defines "types". Competing models may be developed.
