The same is true of ink, plates, film, chemistry and other consumables, though to a lesser extent. Although the e-commerce firms are fully aware of this, the size of this market is dwarfed by print buying and, economics being what they are, they are after the big prize.
Desktop Shopping
From a printing buyer's point of view, the idea of getting a quote for 10,000 brochures, which require four-over-four with spot coating plus folding and cutting, without leaving your desk sounds pretty good. And it should have more than a few printing salespeople thinking about the value they add to the print procurement process. If you add in the ability to just drop the file into a hot folder and wait for the delivery trucks, it sounds even more compelling.