Having worked at one of these firms, I will say that there was general recognition that the system was flawed. Many managers recognized that the best candidate at some noncore schools would be better than the n-th candidate at Harvard.
One key limitation alluded to in the article is that identifying and recruiting top talent incurs high per-school costs (hosting info sessions, maintaining relationships with the U, general brand-building). Since many of these firms turn over half their workforce every year, efficient recruiting is critical.
A further problem that's commonly cited is that identifying top talent is challenging for non-graduates who don't know which majors are easy/hard, what GPA ranges are reasonable, what clubs are legitimate, etc.
Finally, there's strong inertia due to the similarity bias. Princeton graduates like other Princeton graduates and want to hire more of them. The recruiting teams for different schools may even compete against each other over who brings more recruits.
There is also the geographic bias. Only the very large companies can afford to do hiring at schools that are very far away from their headquarters. For example, I go to school in the midwest, and we get Google, Cisco, and a few more big names, but then it drops off really fast.
I hate to disillusion you, but your parents bank account will have more to do with your advancement than any intrinsic ability. Also if you study the last names of the current elite, you'll notice they are the same as bygone elites.
One key limitation alluded to in the article is that identifying and recruiting top talent incurs high per-school costs (hosting info sessions, maintaining relationships with the U, general brand-building). Since many of these firms turn over half their workforce every year, efficient recruiting is critical.
A further problem that's commonly cited is that identifying top talent is challenging for non-graduates who don't know which majors are easy/hard, what GPA ranges are reasonable, what clubs are legitimate, etc.
Finally, there's strong inertia due to the similarity bias. Princeton graduates like other Princeton graduates and want to hire more of them. The recruiting teams for different schools may even compete against each other over who brings more recruits.
[1] Personal and friends' experience