So you say we don't need OOP because you can use this half-baked (non type-safe) way of implementing your favorite OOP feature yourself in your favorite touring-complete language? While omitting the key concept of virtual functions.
"OOP" is a philosophy more than specific implementation details. I've programmed "object orientedly" in any number of languages, many of those with no object orientation helping syntax, like C, assembly, Forth (although that one's more malleable). It's always been about the mental model of your programming, anything else is syntax sugar.
All discussion about "your not doing true OOP because $REASON" arguments are useless, repetitive, and discouraging to exploration, discovery and learning.
I'm saying that OOP as a concept is simple enough that you can do the basics of it in pretty idiomatic and straightforward C, and all the other stuff that we associate with "OOP" is not really universal. And thus it's no surprise that discussions around OOP as a general concept tend to be vague and not very useful.
There are many different OOP styles out there. All one needs to do is to look at the languages that originated the concept, such as SIMULA and Smalltalk to see that they weren't channeling the exact same ideas.