This is just incorrect; there was absolutely a racial hierarchy during the colonial period—the contemporary paintings in Wikipedia page that the person I was responding to linked explicitly showed this, and there’s various citations in the section about the colonial period discussing this. One mechanism of this racial hierarchy was the encomienda system—conquistadors were rewarded for their colonizing with native slaves.

Intermarriage being common doesn’t refute this point. Neither does pointing to prominent mestizos; this is like saying that there wasn’t racial apartheid in the US because there were prominent black figures like Fredrick Douglass, Hiram Rhodes Revels, etc. Mestizos were ranked higher in the hierarchy than mixed white-black, indigenous, and black people—and that’s why there were many prominent mestizos—but that doesn’t mean that there wasn’t a caste system, that’s ludicrous.

If you could give a citation for these studies you’re referring to, I’d be interested. However, considering when another person asked for your source you just linked to another prominent mestizo, I don’t think these studies exist.