After trying it for a few days, I'm finding that this perspective also helps when thinking about it the other way - being someone who provides positive social feedback to others. It gives me a good thing to work towards when I'm having a conversation with somebody - figure out what things the person wants to accomplish / where they want to go, figure out what their plan is and what they are doing to get there, and provide compliments / positive feedback about their attempts at progress towards that goal. If anything, this post just reminded me that one way to be helpful is to encourage people to achieve their goals - by socially rewarding them for making progress, not by merely suggesting that they do something.
Robin Hanson (one of the authors) responds to your review here: http://www.overcomingbias.com/2018/01/elephant-in-the-brain-reviews.html
Surprised to learn I'm not the only one who went with Mealsquares instead of Soylent, due to their use of whole foods. I also only eat Mealsquares a few times a week, and eat a variety of foods with a tendency towards "Mediterranean Diet" types of foods.