The problem with this argument is that it completely sidesteps the issue of how much platforms like Twitter and FB possess quasi-monopolies in their respective

The problem with this argument is that it completely sidesteps the issue of how much platforms like Twitter and FB possess quasi-monopolies in their respective niches. In fact, perhaps Twitter's biggest competitor just got shut down by Amazon. This effectively means that we are back to the old days of newspapers first, then radio, and finally TV, where a small number of media companies control what people read, hear, and see. Except, this time the power is concentrated in even fewer hands. This raises the question of whether something should be done to turn a service like Twitter into content-agnostic platforms that can no longer decide at their own discretion what even the world's highest elected officials can and cannot say.