It's no secret as to why Instagram would make such a move. It's determined to make shopping a mainstay feature, and appointment-based business is a logical extension of that. Garages, restaurants and salons may be more likely to buy those all-important Instagram ads if they know that the promos will lead directly to more reservations. And when Instagram notes that 80 percent of its many users follow at least one business, that's a lot of potential new customers.