What's this weird idea that "B-players hire C-players to make themselves look good?" Are we convinced that all the B-players (let's face it, that's most of us)

What's this weird idea that "B-players hire C-players to make themselves look good?" Are we convinced that all the B-players (let's face it, that's most of us) are so terribly weak and insecure? Is it relative? Would the A-players at Powerset be B-players on a team with Jeff Dean? Would that cause them to hire C(B?)-players? If you hire someone better than your current A-players does that demote them and turn them into poisonous cancers?