It's cut out some expensive variables like film and polaroids and couriers to and from the lab. If you shoot 2000 rolls of film a year, that can add up to huge savings. Photographers can print in their studios or send images to online finishing houses and have them delivered the next day to the client. In other words, photographers can better service their clients and they can do it more quickly.
Good service translates profitably into good economics and future business.
Digital imaging has freed us to be more creative since the results are immediate. Images are now routinely sent to the client for approval during the shoot. Digital imaging has demoted those cumbersome and expensive advertising portfolios to mere doorstops in many photography studios. One advertising photographer is using his laminated-portfolio pieces for dinner placemats. Using them for dinner placemats is my way of repurposing my media assets.