It looks like "substantiated" is another English word which you don't know the meaning.
We cannot even begin to count those threads because the number is ZERO. My cranium has plenty of room for substantial facts and evidence and logic, because I keep it clear of baseless conclusions and myths.
You do not substantiate your views, but when pressed, either "choose not to substantiate (lol)", or, like here, commit some obvious fallacy like appealing to a false authority. WADA doesn't see elite performance benefits because they are not looking at elite performance. They are satisified with subjective non-empirical assessments of a potential benefit, in some cases by looking at small samples of amateurs, in other cases, not even looking at any athlete performances.
The fact is that no one substantiates the performance benefit of drugs for elite performances in men's distance running.
Scientists look at amateurs who may or may not be running their peak performances. In one case, they looked at near elite athletes who tempo'd their time trials (far from elite performances) -- what a wasted opportunity.
What about the athletes and coaches who know so much? We don't have any elite athlete/coach anecdotes supporting elite benefits. Unlike cycling or bodybuilding, distance runners or their coaches don't talk about how doping made an unnatural difference. I'm aware of one athlete who did speak (Kisorio) to the press, but he doesn't even know if he took EPO, and in any case, he got slower while doping.