This is the leftist caricature of color blindness. First and foremost, it was never a conservative approach. The conservative (or traditional) approach was racial segregation and both de facto and de jure white supremacy.

I would disagree and say that conservatives being "I don't care about others" was NEVER a conservative argument, and in fact that would be a caricature. Even during segregation, the narrative was "separate but EQUAL", with a lot of emphasis on "Equal". This argument comes from privilege-blindness and ignoring the experience of being black beyond a superficial sense of equality. The moral case for this is, "Well, as long as Blacks have equal rights, segregation shouldn't matter. As long as Whites and Blacks are going to schools, it shouldn't matter if they are separate schools." This is claiming color-blindness of opportunity and equality. "As long as people of all color have same laws and same punishments, why change anything?"

Both integration and separation from the liberal side, has been an effort at equal opportunity. A black person coming to a white neighborhood, will have protection from crime, access to better schools, access to social events and a political voice. At the same time, a black person having black-only spaces will also be an opportunity to discuss issues concerning their unique experience and having a political voice unadulterated from having to fall in line with mainstream opinions. As long as both can be attained with reasonable dialogue, harmony and support, it is fine, in theory at least.

And you are probably right that this would have happened even if left wing activists used more sensible and justifiable arguments. I'm not sure that I agree it would have devolved quite this much in so little time, though.

This probably has less to do with politics and more to do with a radical change in how media is distributed and consumed, in a customized selective fashion. The information technology of modern times allows people with similar interests to group together and form a political caucus, while simultaneously separating themselves from the realities of the outside world.

This means liberal groups are talking about how cis-white-het-men are oppressing pony-identifying other-kin, while conservative groups are talking about how the red cups of starbucks mark the beginning of the biblical apocalypse and obama is the anti-christ.