A hero in a world of magic, is one who makes a difference in spite of the many challenges posed by that magic. Not one who's just a pawn in a game of wizards, whose decisions and actions make no difference, who's readily replaceable with a golem or summoned monster or off-the shelf mercenary.
The point of a cooperative game is, similarly, for everyone to contribute to winning the game. You don't win that game by making choices to keep another player down for your own glory. Making good choices needs to stand out as a good contribution - even if, say, they're sacrifices. An option in a cooperative game that requires the player to make decisions that net harm the overall chances of winning, in order to appear to be making an important contribution, is a trap option....
Can I just say this is extremely well put? Love it.
Balance-by-pacing CAN make sense in various contexts, even purely narratively, but not in a cooperative TTRPG game if you ask me.