The problem I have with this line of reasoning is that it isn't free speech that's the issue here, it's got far more to do with the echo chambers and feedback loops of social networks. However the solution to the social networks have created is to allow those very same social networks to have total authority over what speech is permitted online.
It's fairly obvious by now to most people that these companies are biased, and even if you don't believe so yourself, the fact they have no reason not to be bias should be worrying enough. How do we explain why extremists like Richard Spencer are on Twitter, but the president of the US and Alex Jones is not? It seems if Twitter's goal is to protect you from extremists they do an awful job, but if their goal is to protect you from popular right-wing commentators they do a fairly good one.
The same is true for platforms. The vast majority of the content on Parler was relatively benign, while Twitter and Facebook hosts far more content which we might consider "extremist". However, platforms like Facebook are too big to have to worry about being deplatformed so instead we distract ourselves by talking about how we should ban a bunch of irrelevant platforms that won't make an ounce of difference in the fight against extremism.
I also think we need to put the last few years into some perspective. The domestic extremism we've seen in the US isn't really happening in Europe. Yeah, we have some far-right and far-left parties, but we always have. I live in the UK and just a few decades ago we had ethno-nationalists organising and staging terror attacks daily during The Troubles. In the 1900s we had the rise of various communist and facist groups all over the West which were arguably far more concerning than anything we've seen in recent years. So how exactly does the last few years stand out from anything we've seen in even recent history? It's different for sure, but it always is.
Finally, I sometimes wonder how much of this panic over the dangers of free speech is manufactured. Free speech has always come at a cost, but we've always understood the alternative where a few elites have the power to forcibly suppress speech is far worse. Perhaps I'm wrong, but it seems to me that social media and much of the media have decided that what happened in the US capitol is far worse than anything that happened earlier this year when entire neighbourhoods were destroyed and police officers were being shot dead in cold blood because of lies and misconceptions being spread on social media. I saw very little talk back then about how we need to ban left-wing platforms or censor left wing activists. I personally saw several people I knew tweeting "ACAB" and suggesting violence is necessary in the summer who are now tweeting how awful the violence in the Capitol was, despite it being far less substantial in terms of deaths, destruction and casualties. I know these aren't bad people too, so I can only assume it was the media which convinced them that the endless rioting, looting and police murders were nothing new or anything to worry about, while a group of protestors storming the capitol has gone too far and that something urgently needs to be done about free speech. I don't mean to make this a right vs left thing, I'm just trying to point out how a lot of the panic over free speech seems to be manufactured, or at least leveraged to further political goals.