i feel like you are working hard to subvert the context of my example.
"Can I spend a few hours setting up an hiding spot so I can bevright in the middle when things go down?" Yes.
But that's not what I was talking about and I think that was pretty obvious.
Not really the the Ranger ability "Hide in Plain Sight" is a minute, not a few hours. But please continue to ignore the main point of my post to pick apart one little example, that has very little to do with the main question.
You original post was an interesting thought experiment from the title
"GMing: What If We Say "Yes" To Everything?" to the premise in your post
"Yes" to literally everything the players asked or wanted to do. No GM control through dice rolls or negotiation,
just narrated the results of the PCs' choices and successful actions?
But since then you've back-tracked saying the game can still say no, even if the GM doesn't due to
something like it is built into the rules, setting or milieu.
At which point isn't that generally how most people GM? I'm not seeing the reason to discuss "Why don't we try carrying on playing as normal?" Your original post had legs (we are on page 16), I'm think you should be making a stronger case for it rather than saying you can still say no, using the rules or setting.
Your original post at least let us consider should the boundary at where we say no, should be moved, or why we might say no in order to make for a better or more interesting game. It being watered down doesn't really leave much for discussion.
Perhaps normally we would say no to magic in a cyberpunk setting because it would drastically alter the game, but because someone said yes we have the Shadowrun setting. Maybe there are things as GM's we might say no out of reflex but if we say yes we will open up something different and new.
Conversely I'm very much of the camp that we don't say no enough in D&D. We allow stuff because it is in the PHB and players expect it, but I think the game becomes more interesting when we say no to things like divine magic, it totally changes the game, but that would be a different but related topic.
Stick to your guns and argue for Yes to everything, even if it is game breaking, it will produce more interesting ideas, than "Yes but...".
Although in actual play I think "Yes but..." is much more interesting than just "Yes" or "No", but there is also room for a "No, but...".