I think instead of dissing the method, he just means he's never been able to accomplish it, bigcountry.
Push-pull does require a little extra agility. It's really hard for some people to push on the limb AND slide the loop up the limb to the nocks with the same hand. Don't know why that is. Maybe some people are simply not wired up in a way that allows it? Who knows.
Putting talcum powder on the push hand helps make the sliding part easier while doing the push.