I was following but til this point. Unfortunately, it is false assumption, fatally false.
I'm going to over-simplify a bit but...The tech companies know what you watched, how much you watched, at what point you stopped, what you shared (or didn't), etc. If Spotify can guess / predict what you might want to hear, the same can be done for other content.
Furthermore, the traditional media companies spent a fair amount on marketing hoping to get the message out to the appropriate target markets. FB and Google already know who is where, when, why, etc.
Correct me, but didn't Netflix use viewing data / analysis to understand which film's and even scenes "worked" and which did not in order to grow their own content.