> Big companies want people who are smart enough to do the work, but obedient enough to put up with all the bullshit that comes with working at a big company. What person better matches that than someone who's able and willing to study for and pass a tech version of the SAT?

Leetcode rather measures whether you are into brutal cramming. Let's put it this way: the kind of people that fits this property is in my opinion often "a little bit special", i.e. not the kind of employee that in my experience both startups and big companies prefer.