Zuck can’t admit that his employees are challenging the business model to its core, even going as far as mentioning Custom Audiences.
Here’s the section on Custom Audiences. Only marketers and industry observers realize this is even possible. Also impossible to opt-out of being targeted with Custom Audiences. “Hiding” these ads deep in the settings is the ultimate dark pattern, a futile effort, by design. 
Brittany Kaiser describes in her book #Targeted how Facebook employees embedded with the Trump campaign helped maximize use of the Custom Audiences feature to microtarget (and conceal malicious messaging).
Facebook’s problem here is perhaps the opposite of censorship. By abusing voter privacy for targeting precision as a business model it monetizes political speech that is limited in its distribution by inescapable voter surveillance.
