I can't speak for the author, but it seems he presented his argument poorly on OOP. I am not sure if it follows the same line of thought I have about OOP, but I regard OOP more as a mental model than a practical one. In that way I don't think everything is an object, more of there are nouns and there are verbs, and everything is to be described in such relationship. I prefer to think and work in component based approach though. Functional programming, on the other hand, is a set of rules over your mental model. Ultimately, I think, it boils down to your mental model which suits you best and, having said that, subjective reasoning. But that's how I think about it, doesn't have to be true.