The question is - why did the Indian caste system evolve? And it wasn't only in India either. And it has existed for thousands of years. Its a provocative question because facts and history will often conflict with ideology.
It doesn't take a rocket surgeon to understand why the areas around Rajasthan & Delhi were/are the traditional seats of power during the British Raj, continuing since India became an independent country.
The whole notion of debating class/race/caste is laughable to traditional cultures like the Indians and Chinese (Mandarins). I mean, they consider it absurd on its face. Only in the US, where it's become a valuable political football, are these ideas entertained.
As you imply, they are cynically exploited by those on the left who know damn well. But, who is so foolish as to give up an important weapon? Only a dunce and a fool, neither of which describes proglib leadership. They need these serfs, the more the merrier, as their bulwark of power.
As I said, profoundly Un-American.
My ideology? Fairly simple, and deepky Red, White and Blue.
“We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.”