Why? She's given her opinion, an opinion based on observation and experience that white people with "points of difference" suffer prejudice, but not the continuous and unrelenting prejudice that black people suffer and she gives some evidence and arguments in support of her opinion. Whether her evidence or arguments are correct, I don't know. Some anonymous (within the context of the article cited) representative of one of these groups claims (again within the context of the article cited) not that her arguments are wrong or that she is mistaken or that his or her experience doesn't tally with Abbott's claimed experience of racism, but instead jumps straight into emotive language and says her letter is "disgraceful". What is disgraceful? The fact she's written it? Her opinion? The fact that she compares other groups' experiences to her own? What? They then badger Starmer to remove the whip. Which he does. Why?