I think in reality though what you're doing is asking people to grind out puzzles until they're good. It's kinda like saying high math scores equal financial sucess. It is true in general but you're basically proxying hard workers not that the basics you test for are right. Getting an A in calculus doesn't mean that calculus helped you be a top engineer I bet most engineers would fail their old tests.

The leetcode interviews to me basically signal: 1. This person is of minimal intelligence required 2. They work hard

The real problem I have is that this system requires an endless calculus test requirement. Most proffessions have one big test to get in then you're basically done. Refreshers are given but once you pass that initial bar no doctor is required to pass their entire medical exam for every interview.

Why not just have a certificate and be done?