system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why the Black Lives Matter protesters shut down Bernie Sanders twice?
gpt
Because it's undirected anger. 

There's mounds of evidence for institutional discrimination against African-Americans, and the prominent shooting deaths of unarmed black kids has been a focal point for a lot of pent up anger. If this was the 60's there'd be a few well known leaders of the black community to help direct this anger to something productive (like supporting candidates or legislation, trying to get changes made in the way police train shoot/no shoot drills, etc). But there are no major leaders of the black community at the moment. 

So, this is what you get, a lot of anger with no one to focus it somewhere productive. Which leads to the misdirection of that anger to someone who is probably interested in helping.