> At Amazon, perhaps one of the largest and most successful employers, the solution to this is that when interviewing, everyone's main goal is to hire people better than the current average of the team.

At this point it's Kool-aid. In practice bar raisers have so much more interview experience that you can very easily pick them out, but so much of their behavior results in simply weeding out the bad.

I have received LOTS of offers from Amazon over more than a decade (only one accepted at one point), and my friend used to be a bar raiser. In his first interview at a new company he was both rude to an interviewee and flat-out wrong technically on multiple points along with it.

You can't raise the bar if you can't pick the bar raisers.