The people don't really have that reach. Social media companies decide what messages are allowed, so only people the companies agree with have any reach on the platforms.
In effect, social media users are just acting as speechwriters for the companies' political views. They submit comments, and mods chosen by the company decide which comments are published. Or sometimes the company simply bans particular viewpoints.
What gets published on social media is increasingly company approved just like any other company's public messaging.