If laypeople cannot know the truth from reading the decrees for themselves, then they have to follow a 'pope' even when he teaches heresy, because they have to admit that "Maybe it isn't heresy after all."
"Have confidence in the Lord with all thy heart, and lean not upon thy own prudence."
You may think that I transgress this verse but in fact it is the contrary. I believe the words of God with all my heart, and reject everything proposition that opposes them.