What is there to be a "ninja" about when it comes to DI? As the article explains in the beginning it just means that you initialize and pass something into what

What is there to be a "ninja" about when it comes to DI? As the article explains in the beginning it just means that you initialize and pass something into whatever depends on it instead of initializing it inside that thing. It's too complicated of a term for what it is because we generally don't say we inject arguments into a function when we call a function. But maybe you mean patterns building on that, e.g. repository/adapter patterns.