The problem isn’t the interview process for software development. The problem is an over-reliance on certificates as proof of proficiency. This happens because of many HR laws and court precedents.
So to stay impartial and out of the courts, the HR people instruct the interviewers to analyze documented experience only. And that’s how this ridiculous situation got started.
Furthermore, If you devise a test, someone will complain that it is somehow unfair, racist, sexist, ageist, whatever-ist. The days when you could look someone in the eye and hire based upon attitude or potential alone are gone.
Sooner or later, someone is going to ask whether the cure was really better than the disease.