Yes, some of the fake accounts - not necessarily bots - are there to create chaos. Russian political influencers have publicly boasted about this.
Of course this is no different to the US and the rest of the West using the media and social networks in other countries to promote their own agenda.
The difference is we're supposed to be immune from having it done to us - and of course we aren't. Because it's no different in principle from a fake advertising and promo campaign, or a fake pro-corporate stage-managed PR campaign - just larger in scope, and weaponised as opposed to financialised.
In reality troll and Tweet farms are incredibly cheap compared to other propaganda vectors, and incredibly cost effective.
At some point knowingly misleading the public for political or financial gain is going to have to become a criminal offence.
Currently consumers/voters have more protection from fake claims about a toaster than they do from fake claims made by a president or a hostile foreign power.
If you're trying to be a genuine democracy, that's a bad place to be.