Spend enough time around hiring teams or recruiters and you'll see that 99% of them are simply very bad at hiring. They put almost no effort into a search. They can definitely find someone. But finding someone that is hired for their actual ability to solve the problems that the shop or team is working on is rare. Leetcode is just a way of culling the herd. The idea that it somehow reflects the requirements of the job are a useful fiction to obscure how little effort most teams and shops actually put into hiring.