You can't compare the idea Lydiard had about East Germany, and the idea I have with Kenyans. Arthur NEVER coached any Eastern German athlete, and his ideas were based on some talk with people involved in the situation of East Germany, who of course told him not the true, but some fake story.
Instead, I coached, and still coach, athletes who have some WR or are in the top 5 in the Worlds, in different events, and I well know everybody of them are clean.
If is true I have personal interests speaking about my athletes, of sure I don't have any personal interest in athletes trained by other coaches, and I say that ALL THE BEST ARE CLEAN (athletes of Brother Colm and Patrick Sang "in primis"). Speaking about these two coaches only (plus myself), I can say that Rudisha, Ronald Kwemoi, Caleb Ndiku, Geoffrey Kamworor, Eliud Kipchoge, Faith Kipyegon, Hyving Kiyeng, Florence Kiplagat, Abel Kirui, Stephen Kiprotich, Wilson Kipsang, Brimin Kipruto, Conseslus Kipruto, Jairus Birech, Thomas Longosiwa, Edwin Soi, Moses Mosop, Nicholas Kemboi, Saaeed Shaheen (only for giving some name of athletes coached by some of us), reached their medals and their record completely clean.
So, Lydiard SUPPOSED, I KNOW. I don't exclude the possibility somebody else can look at EPO or other PEDs, but honestly I don't think the above athletes could have run faster using EPO, and for that reason I don't give any importance to the thesis of Scientists speaking of EPO, without having any experience of training in altitude with the best in the world.