Karma would be a endless puzzle with those who is punished by who again affect everyone around them, be it family, coworkers and friends. Not even a supernatural force could make a fair system if it was based on what you deserved or not.
I see the point of a karma belief as comfort for those who live in misery, and have no way out of it, but it can also lead to accept for status Q, and the belief harm more than help , because they believe the suffering will help them to next level.
My belief about ancient teaching do have reasons more often to comfort, help people, secure the belief system as the main belief, make people think the same, act the same, make accept for the wealthy being wealthy because they deserve it, and control masses of people do not overthrow the system by fear of consequences.
Therecis no doubt the karma system or call it belief, protect the rich and wealthy as well those in power.