Intelligent and reasonable people can disagree - strongly as to the extent of how much of a problem this is, whether or not it is a problem, or whether the cure is worse then the disease.
This also has little to do with fake user accounts.
I haven't seen a claim that fake users played a large role in spreading propaganda or fake news. As far as I understand it the issue lies in what people were sharing and what Facebook identifies as trending news.
That's a pretty different issue from Twitters fake accounts.
I've seen fake Twitter tweets as well that have bad spelling and other stuff in them that it is obviously a fake tweet made by some website fake tweet generators out there. Then shared on Facebook as an uploaded image. If they don't link to the original tweet on Twitter consider it a fake tweet.
Someone I am intimate with left Facebook in the last month, in anger at the way senior management up to and including MZ first dismissed the severity of the problem of their platform being used to push propaganda during the election cycle.
And then stonewalled and foot dragged efforts to correct this. By the account I got the only incentive for action has been unflattering attention at the national press level.
This from someone with a personal relationship with Z.
Make of it what you will. The poison is real.