If everyone is different, how will you decide whom to pick? or filter out. This is why there are standardized tests etc. In our industry it is leetcode, it is a grind, but it is what it is, a standardized filter.

It depends on how your shop is organised. Big corps like interchangeability in their work force, because they wouldn't even know how to allocate their employees as individuals. Smaller shops are better able to exploit specific skill profiles and may even tailor some business decisions to make the best use of their specific strengths.