I really love rap, but it's lyrics, not poetry. As we've already learned, rock, rap, author's song - these are songs, they are adapted to the rhythm and melody, where they should be stretched, where it is necessary - they are pronounced quickly. This is the main difference between a song and poetry - when reading text from a paper or screen, you do not know where to stretch, and where to accelerate the rhythm then normalize it again. This all about rhythm, not text.
Therefore, poetry is a much more linguistic thing, it embodies the language, creating extremely precise images, with the utmost concentration of meaning or feeling in the image. So song or rhythm is simply not necessary.
In general, to write a quality song, you need poetic lines, and that is it! But usually they are diluted with a huge number of words of a purely pragmatic nature - words that are better sung or better suited for reading in rap.
Therefore, if you want poetry, read poetry, and if you listen to a song, listen to a song. The song has a lot of additional instruments, but the voice of Seline Dion deeply penetrating into you is not at all the same as the text of Seline Dion on paper. The song is no better and no worse than a verse, it's just two different genres. As for me, I work as a writer and I appreciate rap and poetry both, you can read more about it
here. I’ll add: even if you remove the music completely, there will be a beat in rap, and a beat is a rhythm, it means changing the verbal structure to please yourself, which means, in any case, impoverishes the language and poetics of it.