Practically, I don't think this ends up being true.

It's like asking Fox news to report something bad about republicans, or CNN to report something bad about democrats. Only the "opposition" will expose the dirtier truths. If you're strongly aligned with a "side", and you avoid listening to the "opposition", you're guaranteed to miss out on truth.

Get your news from a wide variety of sources, because they all have very intentional blind spots.