This is postulating that there's never, ever a case where a player thinks one thing and the GM the other and then saying that you don't need a resolution process because everyone's on the same page. The point of any conflict resolution process is to resolve conflicts. Doing that with an ad-hoc fiat system where one player has all the say doesn't change this. Nor does asking for input make the ad-hoc fiat system less of a fiat system.
To be clear, there's nothing wrong with this, just pointing out that your argument here seems to be just postulating a statement of "but what if everyone's okay with the GM says?" Okay, works great then, we've gone around the circle.