It's impossible to take everything critically, and honestly few will. So the entity with the largest bot army still has the longest propaganda lever.
Twitter and the other social networks know who is a bot, or else they haven't bothered looking. Something needs to force them to act.
I do see one mechanism: the bots go too far, and users don't want to be on a platform where they just interact with bots, so they go to more curated places to get their fill. So the business health of the platform depends on having trust. FB has a leg up on this since your friend list probably has people you've actually met. There the problem is your gullible friend forwarding you crap. A deputized bot, if you will. No level of education helps there.