It is not sexist, racist or whatever-ist to point out that you’re bloody crap at your job and worse than useless.
How I point out you are bad can be.
But when I say “You’re playing stinks and I believe they made a terrible mistake in letting you perform with us” your gender, skin colour and lifestyle preference has nothing to do with it.
And the moment you raise any of those physical traits as a reason of why you are being singled out, you have immediately invalidated any defense you might have used to dissuade me otherwise.
I might have delivered the blow badly, but at no time did I ever level the complaint against you based on some physical trait.
Plain and simple, sometimes you just suck.