Similarly, credentials indicate that a candidate has conaistently passed more screening processes over a long duration of time than a company could practically present to the candidate. Consider that nobody is born into Yale (contrary to popular belief, and any exceptions to this are in the minority). To get to Yale, you effectively must pass through a fifteen year funnel. No company can match that kind of screening rigor, so why not leverage it? From a company's point of view, it would be dumb not to. (Also, think about it this way -- if you are a high school senior with a choice of any school, and therefore one of the smartest in your class, will you choose Yale or a state school? I parenthesized this because it's a straw man argument, but do consider that financial barriers to the Ivy League are basically non-existent nowadays.) Yes, you can get qualified candidates from other schools. But your chances of getting a "lemon" candidate from Yale are, I presume, much lower than getting one from another school. You know that at the very least the candidate is capable of learning quickly on the job. In many industries, especially those where most domain knowledge comes from real world experience, like finance and consulting, the ability to learn quickly is a candidates most valuable asset. If every candidate will arrive at the company with a "blank slate"of knowledge and experience, why not recruit the ones who can fill up their slate the best? This is why finance companies recruit history majors, for instance. They know that success in a liberal arts education demonstrates an ability to learn quickly (not to mention strong writing skills).
I know many people on here are anti-liberal arts or anti-Ivy favoritism. Those arguments, especially the latter, have obvious validity. But I hope this post will cause you to consider the other side of the argument.
Disclaimer: I go to Yale. I realize we are extremely spoiled in the job market, but I also do not necessarily think it's undeserved. It's unfortunate that other people suffer, but I do not feel like we are disproportionately favored. I think a VERY high majority of Yale students are top 1% job candidates. Everybody gets in here for a reason.