https://youtu.be/DkGMY63FF3Q?t=10s
Deciding that you only want the best people is easy. Is there really a business out there who decides they want terrible staff? Determining who those people are is extremely difficult. Even if you are successful in identifying the best people, can you keep them? Whenever I find exceptional people, it takes more than 'not firing' them to keep them.
More realistically. Policies like these aren't designed with any idea of identifying or retaining talent. Instead they are usually a means to affect work culture. Like grading on a curve. It makes everyone work harder.