In a nutshell, you don't have to get why such pieces are expressed, and this piece seems to imply heavily that you believe you have a complete grasp of the situation and yet simultaneously reveals that is not the case.
Take this assertion, for instance: "I imagine someone who has been growing up their whole life being taught that the Confederacy was a group of freedom fighters and that [Black people] just need to stop complaining and work harder encountering elements of [B]lack culture and falling in love." That paradigm seems to assume that that has never happened before, and yet: Elvis. That's what happens in reality in the situation you imagine. They take the elements, shamelessly copy it, and profit while leaving the originators without recompense. Your following statement, "[t]his is someone who may be on the precipice of beginning to understand systemic racism in the United States and deconstructing the problematic aspects of the culture they grew up with," is something of a pot, kettle situation. You think you get it but show you do not.
Instead of complaining about random singular Black people blowing off some steam and stating yet another incidence of injustice -- because they've seen how much White America as a fractured whole simply doesn't listen to or see the evidence in front of its eyes, day in and day out, every single day, of the systemic problems -- perhaps shift your focus to addressing the lie that those people were taught. After all, this is America, right? The First Amendment is supposed to protect all of our rights to speech, right? People will say what they will say.
And we all know that's their right, as unfortunate and inconvenient as it might be. Plus, more people will listen to you, a random White person, expounding upon racism, et al., than almost any Black person. Without addressing the faults of that outcome, it will do us all much greater service if you focused more on correcting the paradigms of bigotry and prejudice than complaining about people commiserating about shared injustice which you have not experienced and do not fully understand.
The reasons for racism and for refusing to recognize one's own racism are not as small, petty, or easily overcome such that the mere observation of *yet another* piece listing more instances of cultural appropriation would sway in either direction. It runs deep, and y'all are tougher than that, right? Who cares what some random person says, right? If it really is all that bothersome, perhaps it's due to the fact that it creates cognitive dissonance within one's own paradigm. That's not the fault of the true message; it's the fault of the paradigm.
In essence, as you say, not only all Black people but also all people of color (or did you accidentally use the two terms interchangeably?) are not obligated to pander to White people, sugarcoat their own struggles, or hide how they really feel.
Take your own advice.
Stop tone policing.