I think they stumbled into being media companies out of naivety and not understanding, initially anyway, that they had duplicated a media company business model

I think they stumbled into being media companies out of naivety and not understanding, initially anyway, that they had duplicated a media company business model with everything except the content generation. they simply replaced the content generation part of the business model with what was being given to them, for free, on the internet by users and other original content creators. when they dropped their initial naivety and took stock of what their business really was it was sufficiently obvious to them that they were media companies and that selling ad inventory was their business. they now fully embrace being media companies but are able to do so in a way that has, at least so far, evaded the traditional cultural and legal regulatory frameworks that other media companies deal with. I think this era will come to an end rapidly though.