LeetCode is a problem that took a famous computer scientist a month to write a paper about, but you have 30 minutes in a proprietary web app to either remember or re-invent it, and pass a test suite.
I'm not even sure that's the wrong way for FAANG to do things, given how many people want to work there. I do know it's a damn bad idea for any place not offering FAANG-like comp, since at lower comp levels you're in competition with a ton of places that don't demand hours of grinding leetcode to prove you want the job bad enough.