YouTube and Wikipedia allowed digital content distributors to enter into the activity at the time of their choice and the mode of their choice. YouTube promotes embedding of its videos in any website or blog. Wikimedia allows its content to be used on any website or blog under creative commons license. These distributors provided lot of advertisement and publicity to Wikipedia and YouTube and also distributed their content. Even in digital media, firms need distributors to take their content to potential users.
Many news organizations feel aggregators are using their content and making money. But if aggregators are not there, their content will not reach the nooks and corners of the digital world. Of course, the aggregators are not appointed by the owners of the digital content. They self appointed themselves. Google search facility was not appointed by an digital content owner. It was created by Google promoters. Of course now, some arrangement may be undertaken to block the search bots as well as to encourage search bots. But still large number of sites get their content distributed through Google search engine without any formal arrangement.
Bibliography for Digital Content Distribution
Interview with CEO of Integral - Digital content distribution firm
Advancement of digital distribution channels
Online distribution channels