Not to mention that altruistic behavior towards members of the in-group is often paired with extreme violence towards outsiders.

Humans are literally Jekyll and Hyde.

"Social systems are much more complex than this simplistic reductionism."

Bit of a misnomer that, surely, as reductionism is all about simplifying things into digestable components.

Also this is an interview piece, its not going to go in depth.

But if you can convince people that there's just one simple way to be (instead of reacting to the situation at hand) then you can sell more self help books / appeal to a simplistic view of emotions where some are 'positive' and others 'negative.'