Well, I made the case to emphasize the word traditional. By "traditional" I mean OOP that follows the popular practices and pedagogy.
Using ECS means totally eschewing things like encapsulation and inheritance. You stop grouping functions and methods together. You basically have "free records" and "free procedures" (or "free methods" if the language requires classes, Kingdom of Nouns style). ECS is a procedural/functional paradigm.
You can argue that this is not OOP anymore, and guess what: I'll probably support you on that! :)
It wouldn't be the first time… https://loup-vaillant.fr/articles/deaths-of-oop