I regularly say yes to work dinners and such that I don’t personally want to attend. That sort of thing is far outside my comfort zone, and that’s exactly why I do it. It’s good exercise to pretend to be outgoing and chatty for an evening. Like any other skill, you get better at it with practice! And the author here is so right: almost everyone else at these things besides the salespeople are probably also introverts…
It's certainly an art and a science to be a good conversationalist, but being in that certain state of mind is "a lot %" of what's needed, and it actually takes no energy or comfort - although as other state, natural introverts enjoy this state for a certain amount of time. It can also take a lot to "get there", though.