If the most-difficult chain wins, period, then Bitcoin is completely controlled by the miners. Nobody else has any say over consensus rules, and even if the miners violated the rules to mint themselves extra money, they would still have the "correct chain" if it had the most accumulated hashpower.

If the correct chain is actually the most difficult chain that follows the accepted rules, then you're still checking with a friend to find out what software implements the correct rules.

Most bitcoin people tell me the latter is the actual case, which means there's a level of social consensus for PoW as well as PoS.