Most liberal white Americans are sadly detached from their own unique cultures and heritage, so they developed a culture of performative self-loathing and insisting they have no contributions. In reality, European culture is so ubiquitous that they can't identify it.
This is the worst type of White.
Not only are they ignorant and unable to step outside of their limited world,
this self-flagellation ritual is a self-centered (I’m a good one!!! Notice me) assertion of superiority (see Žižek’s joke on self-depreciation in the synagogue).