I'm in the latter group. I do my best to embrace the world of social media, and most of the time I enjoy it. Not when it comes to telling everyone to to buy my book, though. My natural tendency is to do that from the bottom of a deep well, while wrapped in a blanket and wearing a gag. A natural salesperson I am not. And I know I'm not alone in that.
Mary Jo Putney once told me writers' conferences are full of introverts pretending to be extroverts. Many writers on social media are much the same. It's a bit easier, because you can do it from the comfort of your cave, hiding behind the computer screen, doing what you do every day anyway, creating a world and characters — only the character you're bringing to life is you. Authorly you — the one who is interesting and glamorous and lives a fantastically exciting life. Not the one who lives in track pants and trainers, who never goes anywhere because, well, that's how you write books, dammit!
But it seems people —publishers — expect you to project some kind of image. And to this end, they require you to provide — horror of horrors!— an Author Photo!