Some of this looks revisionist. It is true that Kenya did well in the late '60s and '70s, and that blood doping was eventually banned by 1985. But ...
Europeans didn't dominate as such in the '70s and '80s, as were just still able to win -- for the men, the best runners were a mix of North African, East African, and Europeans/American atheletes, and for the women, it's true that there were a lot more Eastern Europeans, Russians, Romanians, etc., many with masculine features.
East African participation was more a question of economics for the men -- how many could afford to go abroad to compete in races, besides World Cross Country? This is where European coaches and agents could help. For the women, they simply didn't compete for a long time for cultural reasons shaping views of women in sports.
Kenya did not perform poorly between 1992 and 2004, although their federations often struggled to send their best teams to Olympics and World Championships, and not just between 1992 and 2004. But generally, both Kenya and Ethiopia have been consistently outperforming the rest of the world since 1981 World Cross Country.
A test for EPO was formulated in 2000 and used at the Sydney Olympics, not 2005.
Somewhere around 2008 saw the retirements of greats like El G and Geb, and injuries for Bekele kept him off the track and podium. Around this time, the younger East African athletes started moving to the roads, especially after the format change of Golden League to Diamond League, and following the marathon records by Geb. This paved the way for Slo Mo to dominate the 5000m and 10000m distance events with much slower times, against a much weaker competition training for the roads. At the same time, the East Africans relaxed their views on women competing in sports, following the success of the rivals Dibaba and Defar.