Paleo=no legumes

This post is dedicated to my good friend who wants to know why beans aren't suppose to be consumed while being Paleo:

http://www.cupcakestocrossfit.com/health-and-fitness/are-beans-really-good-for-your-heart/

http://ultimatepaleoguide.com/paleo-diet-food-list/ (this one doesn't really talk about the WHY)

http://www.paleoplan.com/2011/03-15/foods-to-avoid-on-a-paleo-diet-plan/