(I am focusing on the U.S; but posts about other countries are nice.)
Feminism is a social movement that got popular in the previous century; it is a movement that promotes gender equality?
Racial egalitarianism also got popular in the previous century; people were fed up with racial discrimination.
I think egalitarian movements could have easily became popular during this time; egalitarianism promotes the idea that all humans are equal, which is what most civil rights movements focused on; so how did explicitly-stated egalitarian movements manage to not get popular?
I guess it’s easier to rally around a specific facet of it with identifiable victims. Obviously progressive people agree with some form of the idea, even if it’s not how the messaging is done.