The caste system reasonably explains that you are what you are as a result of how you lived a previous life. Christianity claimed God granted divine right to kings and protected the virtuous and meek with rewards or punishments to follow death. Other cultures relied on bloodlines or race to explain social position.
An overwhelming number of people at all times and everywhere remain mired in exactly the social stratum into which they are born. Philosophy and religion seek to explain why. There are exceptions that prove the rule, but by actual count they are few and far between. And movement is restricted _ the old Chinese proverb about “peasant, landlord, businessman, artist, peasant” has a ring of normal truth.
No matter the mythology, such ideas provide a degree of comfort to the vast majority of us stuck with being who we are and were. Only a peculiarly depressing American credo _ born of immigrants and empty land _ declares that one is completely responsible for social position: anyone could have been anything with enough properly applied hard work.
That is laughably false when examined closely. But it is a great comfort to the wealthy elite, just as the divine right of kings and aristocratic blue blood were in the old days. Grants them a freedom to be smugly cruel to everyone else