I reply (WS): For the same reason the Russian-led 'communist' movement was a disaster - 'communism' was but a thin veil for Russian nationalism and imperialism. Did not Marx say about history repeating itselef as a farce?
In that context, I fully agree with the view expressed elsewhere (left conservatism) by Jim heartfield, that the beast advice Marx had to offer was that identity - national, ethnic, religious, ideological, etc. - is something to be overcome, not celeberated, by a radical movement.
In that context, there is nothing scary about the leader of a uiversalist radical movement who happen to be Black. What is scary is a leader who first identifies him/herself as a Black, Jew, Russian, etc. and then espouses a radical cause - it is pretty good indicator that the 'radical cause' is nothing but a coverup for building a political machine.