It’s entirely dependant on the ecosystem you’re surrounded by. If you’re surrounded by wild fruit trees and game is abundant and docile, of course it’s going to be easier to get food than if you have to farm. You can walk right up and pluck it off the trees. However if you’re in an area which isn’t so abundant, or the local population depletes those resources, then you’re going to have to walk farther, search harder, and hunt longer to get enough food to feed yourself and your dependants. Having an agricultural society essentially creates your own abundant ecosystem to “gather” from. Furthermore, selective breeding in agriculture and animal husbandry breeds game and crops that bear larger fruit and more meat per unit grown, making gathering even more efficient.
Where does Watson get this “5-hours will feed your family” number? Seems pretty arbitrary.
Agriculture is much more work intensive, but a more stable food supply. That’s why human populations suddenly exploded during the agricultural revolution. For nomadic hunter-gatherers many children were more of a a nuisance. But settled peoples practicing agriculture had a use for the additional labor.