Interestingly, the banning of all these accounts has caused the size of the telegram groups to increase dramatically and the discourse to get much more violent.

A lifetime ban gets rid of all carrots and all future sticks the platform can offer.

Right now they have an effect through algorithms, but their actions don’t seem to be coordinated towards any goal other than increasing engagement with the platform. This is actively different than pitching centrist content to extremists because the platform owners are centrists themselves.

What if the platform owners become extremists like Parler?

I think giving more control to centrist platforms is the least bad of all the bad options I see. I'm not sure how to mitigate the long-term risks introduced, but the bifurcation of society appears to be a slow motion car crash in progress.

I'd love to be convinced that there are better options, especially if they allowed me to move closer to free speech maximalism.

I think it would help to change middle school and high school civics curricula by adding cognitive biases, logical fallacies (including some basic statistical fallacies), and other tools to better handle social media.

I think shutting down Parler is a necessary response to an immediate and concrete existential threat to the long-term functioning of the American democracy.

However, the deplatforming of Milo was part of the impetus for the creation of Parler. Keeping Milo on and suggesting center-left content to his viewers would have been a better long-term solution, along with suggesting center-right content to viewers of extreme left content. (Edit: actually, come to think of it, you'd want a mixture of center-right and center-left content suggested to both extremes, to make the medicine taste a bit less bitter.)

Deplatforming may be necessary for immediate threats, but it's not a good long-term solution to the problem of polarization. Long-term, deplatforming feeds the conspiracy theories and pushes viewers further from the reach of mainstream platforms.