There's a difference between elite results and non-elite results. For most people, 50-60mpw can be done with a time commitment of 5-8 hours a week. You can also sprint competitively on thie level of commitment, and you can still "have a life." Not so on 120mpw. If you're Bob or Meb, having no non-running life to push your running from 13:26 to 12:58, beat Kenyans at some meets, be an Olympic finalist or win a medal, and pull in a big paycheck from Nike, makes sense.
If you're a postcollegiate who did not at least qualify for NCAAs, having no life for a performance gain of 4% when you cannot win anything meaningful makes no common sense. Even if you become a B qualifier, it doesn't mean very damn much to most people unless you actually get into the Olympics or WC.
Stupid runner tricks.