The most significant check on, and rebuke of, President Donald Trump may have happened already — today. The CEO of Twitter announced that he has been permanently banned from the platform. And the CEO’s of Facebook and Instagram announced that he is suspended “indefinitely and for at least the next two weeks until the peaceful transition of power is complete.”

Twitter was the core attribute and resource for Donald Trump’s leadership style. The ban was prompted by his incendiary rhetoric encouraging the insurrection. But twitter had shaped his entire presidency and had been a huge problem since he ran for the office. He announced policy, fired federal officials, mocked political opponents and ordinary citizens, retweeted conspiracy theories and allowed himself to be totally absorbed by this virtual world. In his hands twitter degraded democratic discourse more than anyone imagined possible. And the activity shaped the mind of the president himself.

Ezra Klein wrote today — on Twitter!— “I’m not kidding when I say I think Trump feared Twitter suspension more than impeachment. And given Republicans in the Senate, and the danger Trump could do out of office, it may, at this late hour, be more consequential.”

Banning Trump from twitter will reign him in, frustrate him, and disable him. But one can’t overstate how important it is to restore democratic discourse more generally. One cannot overstate the corrosive effect, generally, of this medium. It reduces argument to sound bite. It encourages offensive and snarky behavior. The common practices that it encourages by its form diminish respect for fellow citizens of the party opposite.

There are, of course, positive sides to twitter and other social media platforms. Lost friends are found. New friends are made. Collective mobilization can be easier. News can be conveyed more quickly. And so forth. Thus, as a social practice it has good and bad aspects.

But as a principal medium of communication for the President of the United States there is no good side. After Trump, we can hope that future presidents will use this medium sparingly, and that when used its messages will be vetted in the routine way of other messages from the President of the United States.