Because if you challenge any of this, there is just a torrent of abuse
I find it depends how you phrase it. I keep pointing out that there are violent thugs across the political spectrum, and those on the left tend to gravitate towards antifa. So far the response has been tumbleweed.
let's disabuse anyone of the notion that the British were not deeply involved in the development of and directly benefited from, the slave trade in North America
Not sure anyone (okay, maybe one person) was actually disputing this.
It's more that we're being assumed to have American-specific cultural values and biases simply on the basis of our skin colour. And the assumption that the white British population and the UK authorities are in any sort of agreement about basically anything.
Quite a lot of white British people are actually quite keen on holding our own government to account for supporting and colluding with the American regime. I'm guessing that fact flies under the radar across the pond.
The idea that racism against dark skinned people is in the DNA of white people is not really a metaphor for them.
That's a really blinkered view of humanity's capacities. We're pretty big on the demonisation of outgroups generally; skin colour just happens to be an obvious physical characteristic for this to revolve around. In the absence of other skin tones we're perfectly capable of finding a different marker to identify the shat-upon caste.
Just a thought: does it seem reasonably accurate to say the US has a massive race issue whereas in Europe it's more of a xenophobia issue?
And another thought: on the English-speaking internet, the default human is American. This grates.