The total freedom as in the idea of a “sandbox game”for a player to take their in game characters and to do whatever , whenever and however they please at any given moment is an illusionary and ultimately counter productive idea to what a RPG is.
Are you familiar with Apocalypse World? In A Wicked Age? Even Classic Traveller?Because, although a player can desire for and direct their character to do exactly what they want them to. This is not conducive to a game designed around teamwork and group goal completion. Even if one were playing a game with only one player and a DM, it would still not work within the structure of a game. That total free form freedom only works for an individual within their own imagination. No game needed.
I know this is in the D&D subforum, but you made a claim about all RPGs.