You can't just arbitrarily change the scope. The player has only 1 PC and has lost control over 100% of the characters he controls. The same cannot be said about mine, since I control billions and have only lost control over 1 whatever billionths of the NPCs I control.
It's not about length of time. It's about percentage of characters you have the ability to play. So no, it's not a microfractional percentage of the characters the player controls. It's all of them.
The reason you are in the minority, is that most people don't like losing all of their agency and being forced to roleplay in a very out of character manner.
Edit: And yes I am absolutely being forced to act out of character at least some of the time. It's always going to be a 100% loss of agency, but some of the time I will be persuaded to do something my character would never do, or not do something he would do 100% of the time. In those moments the "direction" the mechanics are providing for me to interpret, require 100% of those interpretations to be out of character. Sure I have the option of figuring out how I act out of character, but I don't have the option to refuse the result of the die roll, which would be the ONLY way to act in character.