While the Black Lives Matter interruption of Bernie Sanders generated a lot of debate for whether it was an effective tactic (incidentally I think it was effective despite some misgivings about its execution): the thing that was overlooked was some of the motivation behind it. Looking at articles like "Bernie Sanders Can't Save Black People" the issue wasn't just how to get a more progressive campaign but an outright rejection of any kind of outside help, at all.
Of course the left has a long history of sectarianism but this one runs a lot deeper. Probably starting in the "cultural turn" in universities and then reinforced by social media among millennials, this trend of rejectionism has a lot to do with identity.
If You're Not US, Then You're Not With Us
The argument goes something like this:
1. Privileged allies have never experienced our oppression;
2. they thus do not understand our problems and,
3. because they do not understand they have no place in helping us.
That is, only those who have experienced oppression can understand the truth behind it.
This is actually a clear example of the relativist fallacy, one in which something is true for some groups of people and not others, rather than it being objectively true and thus true for everyone regardless of whether they're oppressed or privileged. To put it bluntly: things like police killings/incarceration, LGBTQ discrimination, immigrant abuse and many others can be understood regardless of whether people are themselves incarcerated, LGBTQ or immigrants. The idea that only a particular group of people can fight to stop them is deeply problematic.
This can also lead to very disastrous results, without outside feedback movements can become myopic do things which end up harming their own goals. For instance, groups like the Weather Underground or Black Bloc became so insulated within themselves that they chose tactics which destroyed their movements and actually made conditions worse.
Now I'm not saying that most or even many activists simply want to reject all outside help, but that the trend exists and needs to be resisted if we're to have any kind of progress. The issue we need to focus on is what is effective at bringing progress in the long-run, not how "authentic" people need to be in order to do so.
Edit: Just to clarify, yes lack of white support, respectability politics, trying to steer the movement etc. are all problems but they're also rightly seen as problems. No one as of yet has addressed how the opposite of rejecting any kind of help whatsoever, is also a problem.
