The selection is a filter for people who are willing to pour massive amounts of free time into preparing for a small subset of companies. It's a great filter if

The selection is a filter for people who are willing to pour massive amounts of free time into preparing for a small subset of companies. It's a great filter if you want someone who obsessively wants to work for you and is willing to sacrifice a significant amount of their personal time for it, but not so great a filter of their competence beyond a basic level. Leetcode is a memorization/trivia exercise, not a reflection of someone's deep understanding of proper coding practices, software architecture, and ability optimize in real world cases (since in the real world you can use google and use whatever libraries you want).