Multiple sexual partners is absolute destruction for a modern family unit that's trying to raise kids. Polyamory is fantastic otherwise - for the right people. And the right people have to a very high levels of self esteem, be very comfortable with their body image and be able to deal maturely with inevitable feelings of attachment and jealousy. Unfortunately modern western life seems to raise very shallow and insecure people so polyamory ends in a train wreck more often than not - it is a one way trip for the vast majority of relationships. My experiences have led me to believe polyamory is a great fit for a very small minority and not something that is socially sustainable on any large scale... which is probably why we have evolved away from it.
That said, your article sounds somewhat academic. Do you actively practice polyamory in your current relationship?