well, i take care to not write in a voice that isn't my own, which is the main problem with many white rappers.
often, when white rappers take imagery and verbiage from black culture for use in their rap, it's drawn from no actual lived experience. rap music, and the culture of hip-hop from which it spawned, is very explicitly a black form of art, and will always be inherently political for that reason. white, cishet, male artists are the only class of artist to have the luxury of never needing to think about what political implications their art actually has when they participate in it, and so when they choose to play in the hip-hop space, there will be friction by default. (note: im not exempt from these conceptions of whiteness just because im queer, nor is any other pasty homo.)
that said, very few people make the argument "white people shouldn't rap at all" in earnest. the issue is often twofold.
one is that most white rappers see participating in a black art form as needing to perform "blackness", as it has been defined to them as an outsider to the group that has been labeled "black," and the lived experiences that comes with that label. how that typically manifests is in a tone-deaf-at-best caricature that rings disingenuously, which is especially apparent in an art form which rewards honesty in expression.
the second issue, and the much more material one, is that white people will straight up have an easier time getting acclaim as rappers because they are white, and that will lead to money and attention and spotlight being taken away from actual black artists in the field-- which is often compounded by the fact that they will then neglect to actually funnel money back into the community of black artists that they are actively benefiting off of.
that's why, in my rap, my only two goals are
1) avoid making money, and
2) talk shit about white rappers as often as i possibly can, including myself.
if someone were to praise party trick for being a good rap song in the first half, i guess i'd feel awkward about being taken at face value. tho with the other ones, i guess i'd just try to be grateful, because i do typically try to write as honestly as i can.
if you'd like to hear more on this subject from someone who's actually melanated and therefore more qualified to speak on it, click here!