If actions that serious have no official consequences, it would make it harder for future bad presidential behaviour to be punished.
And it is easy to see that the book needs to be thrown at as many people as possible who took part in the rampage to deter similar efforts in the future, because Trumpism will continue in some form after the president leaves office.
Trump has only 10 days to go, so this strike against him is most likely to be symbolic.
The Democrats could vote for impeachment in the House but it would have to clear the Senate in a trial for Trump to be removed. Up to 19 Republican senators would have to vote with the Democrats. Any trial would most likely happen once Trump is out of office. The Senate would have to hold a second vote to prevent Trump from holding office in the future.
Just the potential of being the only US president to be twice impeached would be unappetising to anyone else, but Trump reacted to the pressure by saying he would not attend the inauguration of President-elect Joe Biden. He would be the first outgoing leader to snub the ceremony since just after the US civil war.
The Democrats may be content to make a point and add to Trump's impeachment stain in a vote for history before punting it to the Senate. Biden wants to start on the front foot and concentrate on the pandemic rather than Trump.
The process, as the Democrats see it, is also about trying to hem Trump in to avoid doing more damage before his finish line.
Some Republicans have dashed to put distance between themselves and Trump after the insurrection. Senator Lisa Murkowski, of Alaska, said: "I want him to resign. I want him out. He has caused enough damage". Trump officials, such as Education Secretary Betsy DeVos and Transportation Secretary Elaine Chao, are leaving.
Republican senators Ted Cruz and Josh Hawley, who last week led Trump's charge to overturn Biden's election victory by challenging a normally routine congressional process, have been urged to quit by some colleagues and their hometown newspapers.
Other Republicans who voted for that divisive effort, such as senior representatives Jim Jordan and Steve Scalise, are now arguing against impeachment as not helping "unity".
A PBS/Marist poll showed overwhelming disapproval of the Trump supporters' actions. In total, 88 per cent of people surveyed were opposed and 8 per cent supportive. Among Republicans, 18 per cent were in favour and 80 per cent opposed.
Trump is increasingly isolated and under pressure. Even social media outlets have closed him down. The unknown factor is whether he will find a way to lash out.