Stephens says "purpose" is the new positioning. What does he mean by this?

The purpose of a store brand is the reason why the store exists; retailers need to the answer to the question "How can I optimize inventory to carry the widest selection of products?"

The purpose of a store brand is the reason why the store exists; retailers need to answer the consumer question "Where can I get the lowest price?"

The purpose of a store brand is the reason why the store exists; retailers need to answer the question "How can I compete head$-$to$-$head against Amazon?"

The purpose of a store brand is the reason why the store exists; retailers need to the answer to the consumer question "Why should I shop at your store?"