Scale and automation. A salesman in Dubuque, Ill. can only apply his charms to one person at a time, in one location, for a limited amount of time per day. The algorithm industrializes this ability and can hit everybody on Earth at once.

Plus, the experience of eating a cookie has an inherent, positive psychological value, even if the intention is still to separate your from your money. Art vs. Science, God vs. the Devil, etc.