I can't tell if a few folks are being ironic or just slightly ignorant? Apologies if it's the former and not the latter.
But, y'all do realize there isn't a collective 'They' with black folks just like there isn't for white folks? 'They' don't get together and decide to change things up with the nomenclature.
In reality, all sorts of people (usually with agendas) change the meaning of words/labels. This in turn leads to a change in the way some people want to be identified.
For example, some conservatives have endlessly flagellated the word 'liberal' from it's actual meaning - 'a political ideology that advocates free markets, limited government, constitutionalism, rule of law, due process, and individual liberties' to 'DERP, COMMUNIST, main-stream-media-employed, derp, unpatriotic, Socialist, government entitled leech, enviro-nitwit!'
How do you upset the set up? Evolve and modify your identity ... Progressive!