As a non-US person who's worked for a bunch of US companies, my belief is that the Ivy League et al act as a class system, rather than a symbol of educational attainment.
This goes against the stereotypes you read online, but many of them are motivated by a desire to sneer and cut down others’ achievements. Look up “tall poppy syndrome” for one phrase describing this phenomenon.
Again, the fact that entry to the class system can be meritocratic is entirely disconnected from the fact of it operating as a class system.
When I worked at Big tech I remember recruiters (US-based) talking about hiring from approved schools, which were mostly Ivy League.
Additionally, when we were hiring a candidate in Europe, our director wanted to know what school she had gone to. Fortunately, she was an Oxbridge graduate so all was well.
Again, even if all Ivy League graduates were in the top 1% of objective merit, the use of this credential in hiring/firing/other decisions is what makes it a class system.
I have worked with many Ivy League graduates and they were all super smart and mostly effective, but that doesn't change my point.
> rather than a symbol of educational attainment.
Your original argument appeared to imply that it was a system designed to separate people by class, not by merit or educational attainment.
In my experience the people who are that selective about university pedigree are either doing it out of laziness (outsourcing selection process to the university filtering mechanism) or they have a degree from that system and believe that hiring people from it will automatically grant them more allies, thereby improving their own power.
I guess my core point is that those people you note (and I've met loads of them too) would have been equally smart and educated if they'd gone to a less prestigious university, but conditional on their ability, they'll do better at getting higher status jobs because they went to an Ivy League.
> In my experience the people who are that selective about university pedigree are either doing it out of laziness (outsourcing selection process to the university filtering mechanism)
This was a HR level policy at a really fast growing tech company (Facebook, back in 2013). I remember it because I was so shocked that this was a thing (not being an Ivy League graduate myself).