If so, I don’t think you would say the below:
Except it still amounts to "GM makes up how many obstacles you face based on same vague ideas based on the fiction" Which is exactly the sort of decision making you think it arbitrary GM fiat in trad games!
As has already been said this is simply not true. The players choose the Score. They actively have the characters gather information, which solidifies the Score. We learn things in response to the player actions. Those things we learn feed into the Score. This is what you’re totally ignoring.
I think you're just dancing around the actual issue. It is not really about what exactly the obstacles are, it is that the complexity of the situation and the number of obstacles the PCs will face is up to the GM.
If the gather information rolls go well? The obstacles are fewer or less severe. If they go poorly… well things are worse than we thought. Then the engagement roll tells us how things are at the start of the score. And then all of this is done with the principles and best practices in mind. They inform the entire process and should not be ignored because it’s convenient for your argument.
And same for deciding positions and complications and all that. The game relies of GM's subjective and vague decision making, just like every RPG, and it is fine.
Position and Effect are, once again, meant to be clear from the situation on-screen. They’re generally obvious, and the players know what’s determining them. If they don’t, they’re meant to ask… and advocate for their opinion if it differs from the GM’s.
The above is a huge difference from a GM setting a DC and having unknown factors contributing to high it is, and not having to explain how the DC is determined if asked, and also not having to set the stakes ahead of time, or make the risk even known to the players.
If you don’t see that… if your argument is just going to be “yeah but the GM can do whatever he wants” then we’re never going to get anywhere because that’s always the case.
If you ignore what the game is specifically telling the GM to do, clearly and loudly throughout the book, and then also in a dedicated section meant solely for that purpose… the sure, you’ve got a point, Crimson.
But if you’re aware of these principles and what they mean for play and how they inform the GM’s decision-making, then ignoring them seems like an odd way to show that.