Blue
Ravenous Bugblatter Beast of Traal
Players can't declare actions for other players' characters under the proposed method. Players would not, under this method, interrupt another player's character. Or rather, such an interruption would have to be essentially invited since the outcome of any hindrance by one character upon another in my games is decided by the target of the hindrance.
But if you start with something that takes sufficiently long, you're effectively dictating actions - that of not interrupting.
What I will say is that for this sort of thing to work, there mustn't be competition among the players for the supremacy of their ideas and, if there are existing modes of doing things that everyone has agreed upon previously, those things should be respected. Under this method, it would be just as bad to unilaterally break those agreements as it would be to try to tell someone their idea is no good. As mentioned upthread, the players must also have a desire for their comrades to share the spotlight more or less equally. A healthy disdain for bogging the game down with debate also helps.
"Competition for player for the supremacy of their ideas..." - can you unpack this.
I know you said examples were a bad way to show this, and my last example was picked to highlight pain points I was feeling from your description. But here's a common action at my table that has nothing to do with "competition for supremacy of ideas" but all about the decision making process:
Players brainstorm what to do and coming up with a unified plan that they all agree - but it took a few minutes to discussion to get there and it doesn't bear a resemblance to the first idea that came out - part of the beauty of brainstorming is the freedom to throw out any idea without censure.