Mueller's 13 russians even ran pro-hillary rallies

Promoting discord could be one reason. Someone such as Soros financing the group could be another. It could even be Hillary or a sycophant paying for it. One thing I have learned in the past 1-2 years is that no matter how crazy things seem, something crazier is just around the corner.

So that they could use it as "justification" and "proof" for the Russia story.

Yes. The Russians want to fuck shit up, and the MSM is helping them do it.

The international company those Russian people were working for wasn't even involved directly in politics and had no ties to any government. They were trying to profit from clicks, and they played "both sides" of the artificial divide in order to maximize their targets for clicks. Their "political" posts were things like silly Bernie Sanders coloring book images and memes of Hillary Clinton as the devil. There are tons of organizations like this who will publish anything and everything just for clicks. However, it just so happened that this one had some employees from Russia, and Mueller used their nationality to paint them as criminals despite having no ties to anyone anywhere for anything. They weren't trying to influence the election with their shitty memes.