Once one becomes aware of that principle, understands that there is meaningless competition, no winner or loser.
There is simply a balance. A succession of balances. For that reason the roles of attacker and defender actually does not exist.
The Aikido helps us through systematic practice, to realize that we are not surrounded by enemies. We are in a system (family, work, school etc) that changes the balance and we have only have to continue to keep the balance.
Realize that his colleague, the incumbent, the head etc is not an opponent but rather one link in the equilibrium where all work together towards a goal. Without any self-interest.
Because that's just how nature works. And we are part of nature.