The way social media acts as an echo chamber and may intensify extreme viewpoints and isolation from fellow citizens isn't extremely controversial. It has also been leveraged as a tool for good, helping prevent many people from being effectively suppressed, but it's hard to deny the harm that comes from engagement-driven advertisement algorithms systemically stoking people's anger and sense of personal victimization.
The trends of polarization and politically extreme positions in America in particular over the past 30 years are profound and striking.