What is the significance of the commander damage rule in Magic: The Gathering and how does it impact gameplay strategies?

The commander damage rule in Magic: The Gathering is significant because it allows players to win the game by dealing a total of 21 combat damage with their commander. This rule impacts gameplay strategies by encouraging players to focus on protecting their commander and using it as a strategic tool to defeat opponents. Players must carefully consider when to attack with their commander and when to hold back to avoid taking too much damage themselves.