Buried in the Mueller astro-turfing indictment is something that we have long suspected. The Internet Research Agency's "troll farm" is geared to develop audience in socially active communities (e.g through aligned memes), in order to spam them on behalf of anyone willing to pay: 
Before advertising networks can advertise they must build audience. How much of IRA's activities were simply trying to build audience by gaining followers using tweets and memes likely to be shared in those communities?
IRA allegedly also ran kitten appreciation groups. Are we also to believe that these kittens were also a plot to divide America? To not distinguish between audience building and customer advertising payload is sketchy.
The US has 320 million people with a trillion dollar media and cultural sector that employees over a million people. I do not assess that it is possible whatsoever to divide America by trying to "heighten the differences" with a hundred trolls.
Re-enforcing audience bias is exactly what Facebook & Google have been doing at a vast scale by algorithmically preying on people's existing biases to increase engagement. In a more traditional manner, FOX, MSNBC, CNN, NYTimes, WaPO etc, are doing the same thing.
Regardless of whether IRA's activities were audience building through pandering to communities or whether a hare-brained Russian government plan to "heighten the differences" existed, its activities are clearly strategically insignificant compared to the other forces at play.
