I got the same Issue!
It's a MBP Retina 15" 2014. Flickering Pixels all over the screen.
I think they are mainly white and therefore mainly visible in darker areas.
I tried El Capitan and Os Sierra. It didn't change anything.
They are permanently there, so I think it's a Hardware (Screen?) issue.
Maybe a isolation problem? bad connectors?
can't really find anything about that, it seems to be a rare problem.
please help!