Oh yes it is. When Russian (and American) Trump, Brexit or other Nazi supporters use targeting to deliver propaganda to those segments of society most vulnerable to it, democracy suffers.
The US got Trump, the UK got the Brexit, France the shocking rise of the Front National, we Germans got the AfD fash, Austria the FPÖ, Italy the M5S and Berlusconi rising from the dead, and the situation in Poland or Hungary went to total collapse of democracy. Most of this was enabled by propaganda on social media, especially as many newspapers and other real media outlets get their headlines from Facebook and Twitter trending topics.
One thing common to all these "movements": easily shareable (and digestible) "share pics" filled with lies and "alternative facts" creating a massive echo chamber for those lured into it. With an equally massive radicalization feedback loop - like with snuff videos, people always need more extreme stuff.