The author says this about "subtyping" and "inheritance", terms that do not appear in Kay's definition at the top:
Another term that – while not technically necessary – is often associated with OOP is inheritance.
Subtyping is not exclusive to OOP
Evidently, subtyping and inheritance are not mutually exclusive of OOP and in fact often co-occur with OOP. The author certainly doesn't say that they in and of themselves--or "polymorphism" for that matter--causes people to misunderstand OOP (though they might misunderstand the terms themselves, which could cause confusion). You and I don't know for sure what the author's definition of OOP is, and yet you're more confident that it doesn't include subtyping, inheritance, and polymorphism because the author mentioned them? Is that your final answer?
> Says who? You? Did you get a confirmation from the author that this was their intention?
What is it you often say? Oh right: "Did you even read" what was written? In this case I didn't say:
To sum up, the author's argument essentially is, "you critics of OOP are not using the definition that I use." OK. Well, who asked you?
Instead I said
To sum up, your argument essentially is, "you critics of OOP are not using the definition that I use." OK. Well, who asked you?
The careful reader will note that I was asking about YOUR argument, not THE AUTHOR'S ARGUMENT. So no, I didn't get confirmation from the author that this was their intention. I was seeking confirmation from you that this was your intention. Well? Is it?