I would disagree on the self-interest claim. Maybe the author have not experienced breastfeeding at all. To breastfeed is to dedicate a lot of time, energy and effort. I could just easily give my baby the bottle, but for his benefit, I chose not to. Even if that means he'll be clinging to me most of the time, if not 100% of the time.
Maybe the author misused the idea of self-interest. Bonding is one of the multitude of benefits between a breastfeeding mom and baby pair, and for me, that's not self-interest at all.
Aside from the benefits for the mom and baby, breastfeeding has an impact on the environment and the country's socioeconomic aspect. Clearly, that doesn't promote self-interest for me.