Another thing that rarely gets mentioned is that athletics, at least for the world class performers, was effectively professional in Kenya (and Ethiopia) decades before it was in the West.
Roger Bannister, Herb Elliott, Peter Snell, Jim Ryun - all were essentially forced to retire in their mid-twenties and 'get a job'.
Then look at the three Kenyan greats from the 60's and 70's - Keino, Mike Boit, and Henry Rono.
Keino was 28 when he won gold in Mexico. He was less than two years older than Herb Elliott who had long retired. He was only a year younger than Peter Snell, who had retired three years previously. If the sport had been professional back then, he would almost certainly have been facing Elliott and Snell in that final in Mexico, as well as Ryun. (Pretty sure both Snell and Elliott would have prepared for altitude better than Ryun did as well).
Keino continued to 1972 and won gold in the steeplechase. Again - he was less than two years older than Elliott who had retired 10 years previously.
Henry Rono's best year was 78 when he was 26. At the same age, Bannister, Elliott, Snell, Ryun had all retired, as was the norm for non African runners.
Imagine if Herb Elliott had continued into his 30's? He and his coach had plans to even move up to the marathon eventually. He would likely have set WRs in every event up to and including the marathon that would not have been broken until the 80's (and not by Rono).
And then of course Mike Boit. Who was still competing at the top at age 35.
The reason why Kenyan runners could continue into their 30s, when the norm at the time was for non African runners to retire at 25, was because they were being 'rewarded' back home. Financial doping, if you like.
If Keino, Boit, and Rono had all retired by age 25, like Bannister, Elliott, Snell, and Ryun, few would even remember them today.