No consensus is required. Balance is an objective quality that games have in varying degrees. It is not mysterious.
The imbalances in D&D have been measured. Even in the simplest terms that most favor the martial side of the martial caster/gap, those imbalances are quite evident.
That's why balance is a sort of compromise. It seeks to present players with choices they might want - meaningful choices. And to put player choices on an equal footing - those choices should all be viable. "Everyone getting everything they want" is impossible, since there may be some very unreasonable wants out there. By definition, then, some things players might hypothetically want - "I want to be better than everyone else at everything" - that are obviously, incompatible with balance, because, by their very nature, they block others'.
Compromises are like that.