Seeing as I have countered a YANA* with a YANA, I will give an example on my side.
A racial epithet is a description of racially defined superficial difference usually used in some degree of mockery.
The problem with taking a shared history of repression out of the equation is that in almost every case we could propose there does exist a shared history of repression in racial interactions which adds an extra layer of political inference to comments of that nature.
If you were instead to shift it to other descriptions of superficial difference usually used in some degree of mockery, such as hair colour, body shape, notions of beauty and ugliness etc it's easier to imagine a different situation.
Comments of those kinds can still be cruel and even used as socio-political mechanisms of control but there is no defined collective group of historically repressed people connected to those comments, few repressive groups historically associated with their use and few collective groups of resistance countering such comments.
There are no institutionalised ginger hair oppressor groups and the few groups who are organised to combat the jibes against red heads are not taken as seriously as people fighting against racial bigotry.
People of all races can be cruel to overweight or 'ugly' people and while statistical proofs exist that prejudice based on those superficial differences can effect the life chances of people there are no marches for the rights of the ugly or the short, or the lanky.
There is no defined history of systemic oppression.
In an alien or fictional culture it may be that ethnic differences (like skin colour) have never been used in the way we are familiar (or the roles may have been reversed).
A racial epithet would in such an environment have a totally different meaning to that society to that we are familiar with.
Indeed in the future or even in the far distant past of our own species they may have also a totally different meaning.