No evolutionary reason, that is.
On the other hand, if your descendents are born into such deep disadvantage without hope of redemption, that's another evolutionary black hole. The best hope would be to band together with others of similar circumstances and burn it all down.
It's in everyone's best interest for this not to happen. Which leads me to wonder if there is some optimal equilibrium between advantage and disadvantage.
And interesting corollary is that society has basically trumped evolution. There are so many competing contradictory forces that only the most basic changes have a hope of surviving.
Edit:
In hindsight I somewhat disagree with this. Nearly all post-scarcity fictions depict societies in which all are given equal opportunity to realize their personal ambitions. Status and additional allocation of societal-level resources then depends on the outcomes. So for some definition of opportunity I think it is theoretically possible to afford everyone equal opportunity.