I would agree that if your bees are in an area with a great abundance of different pollen that is true. Unfortunately the increasing monoculture makes it more and more difficult to get the diversity needed for strong healthy hives. Beekeepers are a pretty bright bunch overall and they are choosing more and more to spend their hard earned money on pollen sub. because they can see it is helping their bees and not because someone is just making claims. A frame of bees rents for $20 in February and a pound of pollen sub. sells for about a buck.