A living art must address the needs of times, the opponents of the age, the weapons of the era.
Right now that means: multiple opponents, knives, sticks, baseball bats, batons etc...
You (the defender) will be unarmed.
Most of your life will not involve physical combat.
You will be faced with psychological, emotional and physical challenges every day: stress, health, work, family, fear, driving.
A living art must address the nature of your interaction with life.
It must furnish you with the means to adjust to a wide variety of attacks; very few of which will involve physical combat.