This seemingly looks like a reasonable question, to ask "Why do we believe what we believe?" Let's not forget to turn it on yourself.
If I had to consolidate my response to one word, it would be "reason". I can think of at least a dozen reasons to hate Armstrong. None of them can be applied to Geb and Bekele. When you look at all the facts surrounding Lance Armstrong, and the facts surrounding Geb and Bekele, you will see nearly nothing in common. It strikes me as unusual that someone would even attempt to compare them, let alone others fall for it. Why are you/they turning a blind eye to all the existing facts?
And before we ask why, I would ask "ARE we turning a blind eye to Bekele, Geb, etc.?" In the new light of this thread, I'm looking at them again with both eyes, and still see nothing comparable to Lance and the Tour de France.
Lance is a liar, a cheat, a fraud, and he hurt innocent people whose only fault was to speak their mind and tell the truth. This was confirmed by fellow competitors, former champions, former teammates, former friends, former employees, investigative journalists, and a French lab, despite the precedent that Lance set for suing truth telling individuals for libel for 1000000 Euros.
Geb and Bekele? When you look beyond the questions and accusations of anonymous posters, no one, or nothing, is corroborating anything like that. There are no reasons to suspect that Geb and Bekele are lying, cheating, defrauding, or hurting innocent people.
TLW seems to place a lot of stock on his statistical analysis of 5K times during his sliding window of "the EPO era". Is the statistical analysis compelling? It's hard to know exactly when his EPO era starts and stops. Is it "times untouched for 15 years"? Bekele touched Geb's times in 2004 and 2005 -- 5 years after a test for EPO existed, and 3 years after the IAAF initiated out of competition testing. Bekele's best 10K times are from 2004, 2005, and 2008. Is 2008 still in the "EPO era"? In the Tour de France, we can compare climbs like the Alpe d'Huez, from previous times and current times. We see for a 40 minute climb, the riders were climbing 3 minutes faster or more. Yet we are asked to compare them to 7 seconds for 5K and 13 seconds for 10K. A 3 week 3000K grand cycling tour is simply not comparable to a sub-13 minute 5K or sub-27 minute 10K single event.
EPO is available world-wide. In the Tour de France, we know from investigations like the Festina Scandal, Operation Puerto, and now the USADA investigation, that the whole peloton was benefiting -- not only Lance. Americans, Germans, English, Australians, Kazaks, etc. There was no national or regional boundary. Yet in track, it seems that only the Ethiopians and Kenyans and a couple Moroccans, were smart enough, and rich enough, to design EPO regimes that would fool IAAF and WADA and all of the other nations in the world that compete for the same prize money. Kenya is so rich that they can dope nearly 100x more athletes than America. Who is turning the "blind eye" again?
Is EPO really the elusive wonder drug seem everyone seems to think? We don't really know how much it helped in cycling, since the riders were also taking steroids, HGH, cortisone, testosterone. How can we single out the contribution of EPO, versus the contributions of these other drugs, and ignoring the specific differences of when and how much these drugs were administered? We know Lance was doping during the Tour. Maybe other riders only had resources to dope before, counting on the lasting effects. We also don't know how much EPO can help a runner, compared to "legal" and "natural" techniques like "hi-lo" training (helped Wejo by more than 1 minute over 10K), hypoxic chambers (used by Rupp and Farah), and "genetic/environmental" advantages naturally enjoyed by the East Africans from living for many generations and lifetimes at altitude.
To claim that these times only come from EPO also seems to turn a blind eye to all the other drugs that can help, not to mention legal techniques which can bring much of the same benefits.