If you want me "to believe one of the most prolific dopers in the history of the sport", just stop for a moment and pay special attention to your frequent use of the verb "believe". This is a red flag for me every time. We are simply not playing the same game. You want to follow the prophets of your choosing, preselected because you like what they say. I am not interested in the beliefs of others, unless they can back it up with "tons of data". Even then, it is the data that interests me, more than the belief, as even expert beliefs can be skewed by personal or hidden agendas. I see the expressed belief as a speculative hypothesis of one possibility that explains the data.
I don't doubt that many cyclists used EPO, and many cyclists competed with high blood values, and that Dr. Ferrari was prominent in doping much of the peloton.
But if you seriously want to attempt to assess the beneficial effect of EPO, by studying the case of Armstrong, you quickly hit a wall of confounders, as Lance was also taking growth hormone, cortisone, steroids and testosterone, and Actovegin and who knows what else, in a sophisticated plan with a detailed timing intricately integrated with training, designed by Dr. Ferrari to theoretically maximize the benefits. Lance also built a large team of strong soldiers, solely dedicated to Lance's victory, in order to draft him, allowing Lance to conserve energy for the mountain victories and time trials. I don't consider Lance's victories an individual achievement, but a comprehensive strategic team effort. Also, unlike most riders, Lance only seriously raced in 1 grand tour each year, while his competitors raced in 2 or 3 each year (mainly Italy and Spain). What everyone, including Lance, wants to attribute his success to EPO, I see as a product of many factors:
EPO (and transfusions) x HGH x Testosterone x Cortisone x Steroids x (???) x Drafting x Placebo
Greg Lemond was coming towards the end of a long successful career before his hunting accident. If he hadn't been shot, he would have likely won 5 TdF's in a row (if not more). Can cyclists still compete at the top ten years after taking 2nd in the UCI World Championship? I can't think of (m)any examples with careers that long. There was also the question of lead poisoning (or leaked toxins) from the pellets still in his body, and the diagnosis of mitochondrial myopathy.
So you can choose to play the game of choosing who to believe and who to follow and cherry-pick the data you like, based on the criteria of least intellectual resistance, or you can collect all the known data and attempt to perform your own consistency checks.