If someone uses a megaphone in an anti-social manner, that's a matter for the police to handle.
Comparing it to dumb hardware is ridiculous.
Their ability to predict the negative effect of amplifying crazy provides a moral imperative to mitigate that harm. In case you don't understand there is a difference between the platform allowing Bob to tell Sam a harmful lie, and letting Bob tell 200 people who tell 200 people ..., and different yet from algorithmically promoting Bob's lie to hundreds of thousands of people who are statistically vulnerable to it.
This megaphone is a poor example imo. A far better example would be broadcast television. We're now broadcasting everyone straight into not just American homes, but world wide.
So i ask, because i don't know, how does broadcast television differ from a megaphone in requirements? What responsibility is there on broadcast television what doesn't exist for a street corner?
FB has not directly done that, but they have consistently refused to acknowledge that selling the biggest megaphones to the people who create the most "engagement" (aka money for FB) tend to be the types of people who generate false information and outrage.
Their publicized efforts to shut down fake accounts and pages set up specifically to spread misinformation is perfunctory, and simply something for them to point at and say, "see, we're doing things to fix the problem", when they're merely playing whack-a-mole with symptoms, know what the root of the problem is, but refuse to fix it because it's their cash cow.