The one thing that is extremely hard to fake well without some sort of language support is multiple dispatch, the ability to call a method on an object x of type X and have the calling expression automatically "know" which method to invoke depending on the actual runtime type of the object (any subtype of X or any interfaces implemented by it etc etc etc...).

This is extremely hard to fake in, say, C. I mean it's not really that hard to fake the common use case demonstrated in classrooms, a rough sketch would be something like

enum vehicle_type {CAR, AIRPLANE} ;

Struct Vehicle {

enum vehicle_type t ;

Union {

struct car_t { <car-data-and-behavior>} car ;

struct airplane_t {
<airplane-data-and-behavior>
} airplane ;

} data ;

//some common data and behavior

} ;

void func (Vehicle *V) {

switch(V->t) {

CAR :<....> break ;
AIRPLANE :<....> break ;

}
}

But this is a horrible thing to do. First, it's a repetitive pattern, you're basically working like a human compiler, you have a base template of C code that you're translating your ideas into. Rich source of bugs and confusions. Second, it's probably hiding tons and tons of bugs: are you really sure that every function that needs to switch on a Vehicle's type actually does that? correctly? what about the default case for the enum vehicle_type, which should never ever take any other value besides the valid two? how do you handle the "This Should NEVER Happen" case of it actually taking an invalid value? How do you force the handling of this in a consistent way across the code base that always exposes the problem to the calling code in a loud-yet-safe manner ?

There's a saying called Greenspun's tenth law : "Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp". If you ignore the obnoxious lisp-worshiping at the surface, this aphorism is just trying to say the same thing as the article : there are patterns that appear over and over again in programming, so programming languages try to implement them once and for all, users can just say "I want dynamic polymorphism on Vehicle and its subtypes Car and Airplane" and voila, it's there, correctly and efficiently and invisibly implemented the first time with 0 effort on your part.

If you don't want the language to implement those patterns for you, you're still* going to need to implement them yourselves when you need them (and given how common they are, you will* need them sooner or later), only now haphazardly and repetitively and while in the middle of doing a thousand other thing unrelated to the feature, instead of as a clean set of generic tools that the language meticulously specify, implement and test years before you even write your code.

>inheritance, which at this point even lots of proponents of OOP have stopped defending

Not really, there are two things commonly called "inheritance" : implementation inheritance and interface inheritance. Implementation inheritance is inheriting all of the parent, both state and behaviour. It's not the work of the devil, you just need to be really careful with it, it represents a full is-a relationship, literally anything that makes sense on the parent must make sense on the child. Interface inheritance is a more relaxed version of this, it's just inheriting the behaviour of the parent. It represents a can-be-treated-as relationship.

Interface inheritance is widely and wildly used everywhere, everytime you use an interface in Go you're using inheritance. And it's not like implementation inheritance is a crime either, it's an extremely useful pattern that the Linux kernel, for instance, Greenspuns in C with quirky use of pointers. And it's still used in moderation in the languages that support it natively, its ignorant worshippers who advocate for building entire systems as meticulous 18th century taxonomies of types and subtypes just got bored and found some other trend to hype.

>encapsulation, which usually gets thrown out the window at some point anyway in sizeable codebases

I don't understand this, like at all. Encapsulation is having some state private to a class, only code inside the class can view it and (possibly) mutate it. Do you have a different definition than me? How, by the definition above, does Encapsulation not matter in sizable code? it's invented for large code.

>design patterns, which usually lead to loads of boilerplate code

100% Agreement here, OOP design patterns are some of the worst and most ignorant things the software industry ever stumbled upon. It reminds me of pseudoscience : "What's new isn't true, and what's true isn't new". The 'patterns' are either useful, but completely obvious and trivial, like the Singleton or the Proxy. Or they are non-obvious, but entirely ridiculous and convoluted, like the infamous Abstract Factory. This is without even getting into vague atrocities like MVC, which I swear that I can summon 10 conflicting definitions of with a single Google search.

The idea of a "design pattern" itself is completely normal and inevitable, the above C code for example is a design pattern for generically implementing a (poor man's version of) dynamic dispatch mechanism in a language that doesn't support one. A design pattern is any repetitive template for doing something that is not immediately obvious in the language, it's given a name for easy reference and recognition among the language community. It doesn't have anything to do with OOP or "clean code" or whatever nonsense clichés repeated mindlessly and performatively in technical job interviews. OOP hype in the 1990s and early 2000s poisoned the idea with so much falsehoods and ignorance that it's hard to discuss the reasonable version of it anymore. But that's not OOP problem, it's us faulty humans who see a good solution to a problem and run around like children trying to apply it to every other problem.