Racism is wrong and should be opposed wherever it exists.
The ideological purity is that anyone who disagrees with the highly ideological doctrine of "anti-racism" (not simply opposition to racism) is a white supremacist and deserves to be cancelled.
I am not familiar with a "doctrine of anti-racism". In looking it up just now I find this.
Anti-racism - Wikipedia
"Anti-racism can be defined as some form of focused and sustained action, which includes
inter-cultural, inter-faith,
multi-lingual and inter-abled (i.e. differently abled) communities with the intent to change a system or an institutional policy, practice, or procedure which has racist effects."
So it appears that you view anyone who actively tries to counter systemic racism is engaging in a "highly ideological doctrine"? Personally, I call it taking moral actions against those forces which deny the rights of others. I'd call it being moral, rather ideological. I'd call the lack of that, a type of amorality. I'd call ridiculing that, highly suspect.
The problem is that systemic bias is hard to quantify and even harder to correct. Often our attempts at trying to manage such things cause the opposite effect of that which we seek.
Doing nothing and saying nothing of course will not correct the situation. And I don't think recognizing systemic bias in the system is hard to identify. It's very clear when there are policies put in place that discrimination against blacks. Of course there will be blow back when you try to challenge that, but remaining silence only allows it to continue and to grow.
Personally, I don't believe making everyone hypersensitive to race, pathologising whiteness, and ruining people's lives over anything not seen as sufficiently pure in this regard is counterproductive.
Hypersensitive? The problem is a lack of sensitivity. If someone feels they are being "preached at", for what should be normal human compassion responses, then I'd say the problem is theirs. I'd call that hypersensitivity a reflection of something they are uncomfortable with personally, a "methinks the lady doth protest too loudly," senario.
As far as pathologizing whiteness, again, I think that is in how someone hears that. What is it they are hearing? That they should feel guilty about have social and economic advantages because they are not black? While that is factually true, how someone chooses to internalize that fact, feeling guilty, is entirely their own thing. Blaming the messenger, doesn't change the message. That's something I don't think people realize, hoping if they can make the messenger look bad, the message can be ignored.
Sure, you're going to have some self-righteous ones who acts the same as the self-righteous Christian who tries to feel morally superior because they can point out the flaws of sinners. But to focus on those, can easily be used as an excuse to not listen to the truth that are touching on. Everyone is going to act differently, but it's not about them. It's about racism and overcoming it. That includes everyone, themselves included, left or right, liberal or conservative. It's everyone's problem.
There is scientific evidence that the more people become aware of racial differences the more they discriminate, yet even advocating for a goal of a colourblind society is 'white supremacism'.
Are you proposing no one say anything? Just let it self-correct? Let George Floyd just be another victim of systemic racism, and let people figure it out without all this fuss?
How can you solve a problem that you can't even discuss in good faith?
Good faith is acknowledging there is a problem, and that it needs to be addressed. All that other stuff is just distractions. "Look over here at them thinking they are so righteous". That's not looking at the situation itself. That's just an excuse to not look.
What HBO is doing seems reasonable, I wouldn't describe it as courageous though.
Not caring what right-wingers say, I suppose is a step of courage though. Look, we even started a thread calling what they did "censorship". How sensational, and untrue. Again, the effect is "Look at HBO!", or "Look at these Libs!". It's curiously not however, "Look at my own role in racism". It should be, because we're all part of it. It's part of our culture.
In general though, there is a lot of self-censorship out of fear, especially as one of the preferred tactics is to get people fired and ruin their entire lives for the crime of heresy (and I'm not talking about blatant racism either, it's often liberals who are just not being woke enough).
I'm not sure who are what you are referring to. But I can this, what you accuse the left of doing, the right does the same. This is a behavioral thing, a developmental thing, not a political thing. Extremists on the left and on the right, are solemates. They are one and the same thing.