If I wanted to just attack and destabilize society I'd have armies of bots supporting all the most divisive positions on all sides, as well as promoting incoherent and irrational positions.
The idea is just to divide, confuse, "flood the zone with shit" as Bannon likes to say.
It seems like people are actually not bad at noticing likely bots arguing against their favorite positions, but are blind to the possibility that there could be bots pretending to be on their side. The most corrosive might be bots pretending to be on your side but advocating subtilely wrong or unnecessarily divisive formulations of your ideas, which in turn are more likely to influence you because they seem to be on your side.
Phrases come to mind like "vandalism of the discourse" and "intellectual terrorism" where the goal is not to promote one specific idea but to destroy the discourse as a whole.
That certainly looks like the world we're living in.