As a former newspaper columnist, yes, the AP Style Manual (version whatever) WAS the “Gutenberg” to be followed.
Even in ‘writing schools’, which I am a graduate of, the AP Manual was one of those ‘must buy’ reference books for the taught courses. My mentor was a former chief editor of a Philly ‘paper, so ‘the style’ became rote.
There sre enough people out there that can’t read between the lines so phrasing and word usage can easily lead them astray.
I have a daughter in journalist school. The AP style book is still being used and required.
I stil have mine but haven’t looked at it for years...
AP = Turning the Fourth Estate into the Fifth Column. I believe the AP is the enabler of The Swamp. The Swamp is able to exist because the enabler keeps The Swamp from public view.