Don’t get me wrong, Twitter is important, but not so much because it’s the only way for governments to communicate effectively with citizens. That’s absurd.
Government has long had the power to commandeer broadcast media when it needs to get a message to the people ("We interrupt this broadcast...") Do we want to do away with that?
For all its flaws, the government is still something every citizen of the US has a say in, however small. I'm not willing to trade that for rule by Twitter executives, however well-intentioned they might be at the present moment.
No, it hasn’t (outside of, say, the Emergency Alert System.) Government addresses (“We interrupt this broadcast…”) are a subject of requests for air time, which broadcast networks usually (but not always) grant.
A decent enough basic explanation with some historical examples is here: https://entertainment.howstuffworks.com/major-networks-carry...