When we talk about 'the free press', what do we mean? What is it that we want the press to be free from, exactly?

To me, it's freedom to report honestly, free from pressures that might encourage dishonesty. But if that's the case, 'the free press' is largely a myth because no media outlet is free from those pressures. In turn, that begs the question, who benefits from perpetuating the myth of a free press?