For many years, the conventional wisdom was that only highly biased, less educated media consumers would put partisanship over truth—in other words, they would believe news that confirmed their worldview, regardless of whether it was true.
I know I certainly am. In the US, if a politician with a D next to their name is telling me something, I know they're trying to exploit me on behalf of the owner class. On the other hand, if it's an R politician, they're trying to exploit me on behalf of the owner class and murder me for not being exactly like them.