With respect, I never mentioned a high-prepped module. A collaborative table is a great thing. And by collaboration, I assume you mean that the players share, and then the GM reciprocates, meaning they add things the players shared. That is called an RPG table in my world.
And that table is much more consistent if the GM has done a "boatload of prep" than doing no prep.
Correct. That is why I said it is both. But, and I am going to assume here, we have all played a video game where one storyline is better than the other. More satisfying perhaps. We have all seen a show or movie where the story unravels or the ending is "meh" and thought, they could have done better.
The reason they could have done better is because they should have told a story.
I am fine with the fact that you believe so. But it is not true. Be delusional or fill yourself with false beliefs all you want. Then dig down, deep inside, and you know that a story line that is prepped, be it in Hollywood, novels, or RPGs, most of them have greater internal consistency. As I said before, you may be able to come up with an outlier, but it is not the norm. Go ahead and try to find a great RPG computer game that pulled your heart strings and wasn't plot diagrammed. Find a great internally consistent movie where the director just followed random things. Or find a great RPG where the DM had no idea for their world or plot line. All of those might exist... maybe??? but they lean towards internal consistency.