Maybe its because in general, historically, we might have more to be ashamed of, than to be proud of.
Nazism, colonialism, predatory capitalism, dystopian communism, and white supremacism, are all white things, that make difficult bragging or comedy.
We are far from reformed from a criminal background, as long as we carry on some of those practices, whilst whitewashing the shameful history.
Banning, destroying, and generally cancelling all historical artifacts, words and concepts, that might remind us of it pretty much cuts off all routes to meaningful discussion.
One day we might ruefully accept that this is our very own, embarrassing, but real, historical culture, that comedians of all colors might beat us up for, without us getting “Triggered”.
Still seems a long way off!