"Balance" gets abused a lot, as a term. It means multiple things, and it results in people talking past each other.

Intra-party balance -- that is, everyone in the party being approximately equally capable -- is important for most tables because most people resent getting clowned on by their so-called allies.

Creature/encounter balance is not about forcing the fights players get into to be fair, but about having a reliable way of telling how hard the fight will be. That knowledge is not an obligation to make the fights fair.