As a former lawyer and judge, I am familiar with the use of certified copies of official documents, like a death certificate or an honorable discharge from military duty. Such copies are accepted as if they were originals because of the official certificate. This acceptance is based on the fact that anyone who doubts the authenticity of the content can verify its accuracy by going to the original.

So it is with a prophetic revelation of a prophet of God.

He is the certifying authority that his teaching or direction is from God.

Anyone who doubts this--and none are discouraged from personal doubts--can verify the authenticity and content of the message by checking it with the official source by revelation.