This is interesting. I had never heard this before. Is there any research on this? For that matter, is there any actual research showing that leetcode-style interviews actually do predict performance? If so, do they do so any better or differently than an IQ test?

I would almost believe the opposite: if you actually pass those tests with flying colours, it shows me that you believe you needed to do that to be hired, while someone who's actually experienced would never in a million years step down so low.

Well said. Just like in college, calculus (not analysis) and organic chemistry are used as filter courses. Of course, why the two courses, especially organic chemistry, are so hard to American students is another topic. I personally think that it shows the failure of the education system of the US.