What is sold is advertisement, thus the paying customers are the advertisers, and what is being sold are the users themselves, not their content.
This means that the source of value that becomes Facebook's profits is the work done by the workers in the global fields and factories, who are producing the commodities being advertised to Facebook's audience.
The profits of the media monopolies are formed after surplus value has already been extracted. Their users are not exploited, but subjected, captured as an audience, and instrumentalized to extract surplus profits from other sectors of the ownership class.
Sharing economy companies like Uber and Airbnb, which own no vehicles or real-estate, capture profits from the operators of the cars and apartments for which they provide the marketplace.
Neither of these business models is very new. [...]
Rather than subvert capitalism, "sharing" platforms have been captured by it.