It's because the thing is so evil that even your average normie would find it appalling. I can sum it up as "teaching the black kid to hate the white kid and the white kid to hate himself"; and everyone understands why it's evil (unless they are also evil).

As a response, they Left, and many of the CRT-ers themselves explicitly lie about what it is at all times. They are desperately lying about their own work, their own examples, their own publications, because it's so unpalatable.