Pretty much everyone gets exposure to contrary views, and they probably wouldn't seek out echo chambers for recreation if they didn't! Most people don't actually want to argue about politics when they vent on their social media, they want to engage with their friends, who probably feel similarly to them. There's no need to worry about these conversations being unbalanced any more than you worry about balance when line workers talk shit about managers and managers talk shit about employees. If people wanted balanced conversation, they would join a political debate forum rather than a social network that connects them to their real-life friends.