When I play a character who's subject to IC discrimination, it's because there are aspects of the theme or setting that I think are interesting to explore with that specific type of character.
Like, on a GoT game in the long-long ago, I played a bastard (the illegitimate kind). There were specific class and personal issues I wanted to mine for dramatic purposes. I did this! There were character arcs! It was good times! Some people do enjoy playing off IC adversity. I have zero OOC issue with players who just don't want to engage in this stuff, but it would've been weird and not particularly fun for me if this character had been ICly legitimitized and never faced any sort of social side-eye.
Like I don't get the extension of the argument from 'players should be able to opt out of dealing with racial and homophobic slurs that exist IRL' (which I basically agree with) to 'all IC discrimination serves no dramatic purpose', if indeed that is the argument that is being made.