So, set aside the specific wording from WotC for a moment.
Answer the question for yourself. As you play it - Is the game three pillars, and ONLY those pillars? Or is the game supported by three pillars, with some extra stuff around it too? Or...
Take for a moment the idea that "three pillars" is a model for the game. A way to look at it, its design, and structure. The model doesn't have to be 100% accurate and precise! You can decide for yourself where that model fails, and where it is useful.
I would take the "three pillars" as being a basic point of where players wind up spending most of their attention - combat, social interactions, and exploration. That seems fair enough. But it does not seem fair to say, "Every individual action done at the table is 100% under the bailiwick of one of these pillars." That's one of the basic mistakes of using any framework - be it three pillars, GNS theory, or what have you. Mistake your conceptual framework for all of reality, and you wind up having issues.