Why do organizations like IABD continue to use the word “Blacks” even though it’s considered outdated in daily conversation?

I have a white boss who insists on referring to black people as Blacks in daily conversation, entirely because IABD (International Association of Blacks in Dance) continues to use that language. my black coworker is losing her mind over it and we’re all struggling to verbalize to her why she should just say black people or black dancers.

my gut understanding is that IABD continues to use it because of historical context/significance, and ultimately because the way black people talk about themselves is always going to be different than what’s considered appropriate for other folks?

something that makes sense to me is that i am not bothered by queer organizations/people saying that they’re “for the queers” but i would be really grossed out by a cishet person calling us The Queers, as opposed to queer people.

is there a way of explaining this that i’m missing? i just want to help my coworker navigate an uncomfortable conversation!