Anderson Silva took an L against Ryo Chonnan, GSP took an L against Matt Serra, BJ Penn took an L against Jens Pulver, Jose Aldo took an L against Luciano Azevedo.
So you're saying none of the all time greats are actually great if they ever lost in their career....? Amanda Nunes beat Miesha Tate, Ronda Rousey, and Cris Cyborg. In a row. It's like if someone set up a gauntlet of women we consider to be great mixed martial artist and she came along and wrecked it.