Early in my working career, I got an unheard of raise of 9%. Another worker got wind of it and was unhappy with his 5% raise. He was told the raises were merit based. He became a staunch advocate of our engineering union. The union sought ot define merit and how much merit was worth. Over the years I watched the top percentage fall as the worst percentage increased until almost everyone was guaranteed almost the same increase regardless of worth. Every engineering salary was trending toward the average.
Over the years I've heard stories about playing ball games without keeping score so no one will feel bad about losing. That might be true but one should also understand that no one gets to feel good about winning either. I'v also heard that giving grades from A+ to E or F may be facing a similar fate. When high schoolers start failing SAT test at too high a rate, the tests are revised in a manner that allows more people to pass, a downward spiral.