However, I do believe that YC tends to be somewhat more egalitarian and merit-based compared to others, although it’s not by a significant margin.
What if regarding slavery or horses as transportation people were like "that's essentially how the world operates", not that investing has anything to do with those, but that this excuse doesn't add a ton of insight if you think about it.
There are a lot of ways the world has operated that are not fair or optimal. It would be a logical fallacy - an appeal to tradition - to use that as an argument against the way things could be, or according to OP the way things should be (are intended to be).
Investing is a regulated activity that affects the economy and individuals, so I think it's at least worth exploring things like nepotism and exclusivity when it comes to the flow of capital. And it's obviously important to notice when the same relatively tiny group of people keep receiving the majority of "acceptance" (investment) while the vast majority outside that circle are totally ignored and/or marginalized.