Some Kenyans and Ethiopians have been caught using those drugs. So have some Americans, some Canadians, some Germans, some Chinese ... you get the idea. It's true of elite athletes in any country and any sport, just about. Generalizing from "some" to "all" for one group while ignoring prevalence of the same problem in other groups is not a good look. No suspicion has fallen on the folks who currently hold world records, won the last several major races, etc.