Candidates spend their time on stupid coding questions all day instead of actually coding something useful or that they can learn from. I have a relative doing exactly this. No idea how to build a simple RESTful API, yet spends all his time on Hackerrank posting on linkedIn how he's in the top 'X' percent.
When they get hired and put on a "real world" project they are absolutely lost :(.
I also tried Triplebyte after seeing ads on Reddit. Passed a few tests and nothing really ever came of it other than an email.