You can say all that, but I've never seen a D&D game that didn't involve a a small to significant amount of shenanigans, except one incredibly po-faced dungeon crawl I once witnessed, carried out by a DM who definitely hated fun, and some of the least imaginative people I've ever played with (I was amazed they were playing RPGs at all - they didn't seem to be having a great time).
It definitely does in some groups, and your definition is unnecessarily narrow - any particularly ridiculous attempts to trick people which nonetheless seem like they might work out fall within "shenanigans" as well as "social". For example, when my main group came up with a completely demented plan to basically infiltrate a place by representing themselves as traveling wine salesman and wine educators - it was really the latter part which shot things into the shenaniganosphere. I can't even remember exactly how it all worked but hysterical and honestly it was situation-specific-enough (including them guessing stuff they hadn't actually found out) that I had to allow that it did. They improvised their way through all my attempts to poke holes in it with a fluid-ness we still talk about to this day. They skipped literally an entire dungeon that way!
As an side, D&D's three pillars are pretty arbitrary and definitely do not cover everything that goes on in D&D particularly well.