> the purported golden age of impartial truth-seeking.

It's constantly been with us since the beginning of the republic. Several of our founding fathers were actually publishers.

> this consensus

Consensus doesn't exist in a vacuum. It's a product of an interest in profiting off the news. It seems obvious from this vantage what the fundamental problem is and why "journalists" are not a homogeneous group with identical outputs and why terms like "main stream" even exist.

> it helped with social cohesion and national identity

Which is why the FBI and CIA target it for manipulation so relentlessly.