The point of hacker rank isn't to tell apart the code-monkey from the expert who is rusty. It's to find the people who are willing to spend hundreds of unpaid hours grinding leetcode. The thought process is that you only need two things to become a successful developer. Baseline critical thinking skills and the willingness to spend 60 hours a week reading up on best practices. If you can pass leetcodes interviews you've probably got both those. Figuring out if someone is an expert coder is hard, figuring out if they have these skills that you believe are required to become an expert coder is easier.
Still, it makes little sense if the applicant holds a BSc/MSc/PhD on the subject. These degrees require many more hours of commitment than the time you need to master leetcode. Moreover, the scope of leetcode assignments is rarely broader or deeper than an advanced-course assignment. Just take 5' to go through their academic record, take their professional experience into account, and you're done. No need for dubious "magic" solutions and useless charades. Even if you include cheaters, what makes the recruiters believe that someone who has cheated their way through a comp-sci master's program will have trouble cheating to inflate their Hackerrank?
