You don't get it. You need background to compete at your highest level. Capilaries, mitochondria, myoglobin, etc.
Why could Haile G. run 27:30 for 10k at age 19? Because by that time he had run tens of thousands of miles. How could James Kwalia run 12:55 for 5000m as a junior? Because he ran tens of thousands of miles.
Kids have fun because they improve. Listen to greenliner. His kids went to York, ran a whole lot, improved and ran well. And you could say, "Well, where are they now?" First, everyone is not so talented to make it to higher levels and second if you lose the desire to compete (for whatever reason) you can't coach it.
Name your examples of successful athletes of your approach and for every one I will put out a slew of guys who ran a ton of miles in their youth, at relatively low intensities, and are more accomplished.
People say, "Well, Bob Kennedy didn't run that much in HS." True, but how long did it take him to run sub13 and 7:30? Until he was 26. That puts him 6 or more years behind comparable competitors and gives him 6 or more years less in his career.
People say, "Well, the Kenyans run fast but they have huge burnout rates." True, but you must think why is it they burnout/stop racing? On one hand who is coaching them? If they have a good, intelligent, long-term development coach like Renato Canova, they can have very long careers. But often times they are at various camps where they get the shit beat out of them and whoever runs well gets the ticket. And even individual managers can do that. They put them through insane workouts and overrace them and then they're done. And even then, running to many Kenyans is a way to secure financial stability. So they run, make some money and buy a goat farm, or go to the US road circuit to clean up for a while and then go back. Daniel Komen is an example of both. Kim McDonald beat the shit out of that guy and he ran superhuman times -- FOR 3 YEARS. And then his career was over. He was burned out and he had earned the money he wanted so that he didn't need to run anymore.
Name your low mileage kids. Like Mike Stember (this is not personal to Mike, I'm just using his career as an example)? The man never trained at high volume and was always doing intervals. Like Mike Grannville?