I wonder which fraction of the code actually benefits from these techniques though. Certainly I become suspicious from the fact that examples like in this artic

I wonder which fraction of the code actually benefits from these techniques though. Certainly I become suspicious from the fact that examples like in this article always tend to be of a very narrow, specific kind. In my experience, every worthwhile piece of code outside of certain libraries has enough of what you might call "business logic" that these theoretically clean approaches no longer apply to. This has been true across lots of domains, from games, to CRUD, to compilers, to combinatorial optimization algorithms. I'd go on to argue that the interesting core of all those problem domains was precisely in the areas that couldn't be solved using cute techniques like OP's.