The ways in which social media amplifies fringe viewpoints and enables them to influence public debate and intermediary groups in society should thus be a greater concern than mass propaganda.

I fail to see how the two are mutually exclusive. Couldn’t mass propaganda be disseminated using the same mechanism you’ve described here? Feed your propaganda to the fringe kooks, and then let them spread it for you across social media? Because that’s been my perception of what’s been going on from the beginning.