Prior to social media it was demonstrably harder for people with "extreme" (for all values of extreme) views to spread their message and find like-minded people. Not impossible, but definitely not nearly as easy as it is now. Social media platforms aren't the cause of misinformation, they're the cause of the rapid dissemination of it.

I don't think shutting them down will stop it but I think a lot of todays hyper-partisan inflammation of the citizenry is owed to these platforms and their encouragement of any and all "engagement" on their platforms in service of ad dollars. These companies know how harmful these products are but since they're profitable they ignore the findings. I would argue that Meta/Facebook is the Philip Morris of our generation.