> I am not sure why would I want to do that.
> As a leftist (being pro-equality), I don't really want there to be anybody who got a bad deal in society.
I think the issue is that there are very large numbers of people who have gotten a bad deal in society. Investigating every individual, individually, is probably time and cost prohibitive. So investigating by common features across groups of individuals helps to try to maximise that return.
While I think we'd all like to live in that utopia where nobody gets a bad deal in society, it's not the world we inhabit today, not even close.
"I think we'd all like to live in that utopia where nobody gets a bad deal in society"
This is objectively not true. Many people don't care about other people getting bad deal.