I don't claim there was a single ideology underpinning the reasons for the calls for social change. I'm saying that there are usually people (radicals, progressives) calling for social change, and others (conservatives) warning against it, and the rhetoric employed is similar throughout history (e.g. "if you only asked for a little less", or "the previous demands were reasonable, but the new ones are excessive"). That's understandable, as conservatives throughout history sometimes don't like to appear -- possibly even to themselves -- as the enemies of progress so they claim to be in favour of "reasonable progress," but whatever it is that the progressives currently call for is unreasonable; of course, a generation later, the story repeats. Ideas like women's suffrage were deemed outright preposterous, risible, and too silly to seriously consider; in fact, it took actual acts of terror by feminist activists and a world war to get them the vote.
So if you want to compare current demands to previous ones in order to explain the reaction to them, I'm saying that you should also compare current reactions to previous ones. "Previous demands were reasonable, but now they've really crossed a line," has been pretty much the conservative refrain going back millenia to the patricians and plebeians of ancient Rome. All of this is why I reject talk of "excess." It's just how conservatives speak of social change for millenia. You can say that you agree or disagree with some policy, but the "this is too much" line is just a cliché.
Criticizing "defund the police" (as in, actually defunding the police) or normalizing the use of "whiteness" as a pejorative is not a bad thing just because conservatives do it. In fact, conservatives are doing society a valuable service by pushing back on those things. I'm quite sure in the retrospect of history, those will be proven to be "bad ideas progressives tried at one point" rather than examples of real advancement.
Having said that, I'm fairly certain that in the retrospect of history, conservative pushback on the change in our understanding of race would look like another incarnation of white supremacy, and would appear as horrendously wrong to the people in the future as segregation appears to us to day, so much so that the conservatives of the future will use them as an example of something that is obviously right, unlike whatever social change people call for then.
There's also lots of progressive ideas that turn out to be ideological dead ends. Prohibition was heavily supported by women's suffragists, and was seen as a progressive social reform. Building highways through the middle of cities was seen as a progressive and futuristic approach. Eugenics was, of course, the nadir in terms of progressive ideological dead ends in the 20th century.
Take the example of same-sex marriage. Academics like Judith Butler have consistently opposed same-sex marriage because they believe it does not go far enough to dismantle, and indeed entrenches, what they see as a repressive, patriarchal institution: https://theconversation.com/why-same-sex-marriage-is-not-the... ("But there is actually a large amount of anti-homophobic academic and everyday writing from thinkers and activists that probes the numerous problems associated with same-sex marriage."). Andrew Sullivan recognized this back in 1989, arguing that same-sex marriage was the conservative option to accommodating gays and lesbians, compared to the radical dismantling of traditional norms that people like Judith Butler espoused: https://slate.com/news-and-politics/2015/06/gay-marriage-vot....
That same Judith Butler is a leading academic in the field where "whiteness" is used as a pejorative and "objectivity" is attacked as "white culture." Maybe that, too, is an intellectual dead end, not real progress?