This is what happens when actual ATHELTES get into track.
When track is a secondary sport, people in most of the world will play even D-level soccer/football/basketball/hockey etc (depending on the country) before they would focus on track. (MOST people.)
If the same athletic base that makes up the NBA and feeder teams, or the UK soccer system, had focused on track the 400 and 800 would be on another planet right now.
There are very few countries where top talent is streamed into track -- even in Kenya the average-sized and bigger kids generally want to play soccer, and it is the shrimps who are spotted as runners (and can't hold their own in soccer). Rudisha being the exception.
When ATHLETES are exposed to and pursue track and field, you get guys like Riley McGown and Julius Yego "surprising everyone."