Let's imagine this was implemented. For every post on Facebook, Twitter, et al, a counter-point from the other side was included. Would this change anything?
Maybe not. The narrative right now is that the social giants are forcing people into media bubbles because this drives engagement. Including counter-points would burst the bubbles and we should expect a drop in engagement on the major social media sites. But would it lead to a drop in engagement overall? Wouldn't people still seek out the news that reinforces their pre-existing views?
The narrative should be inverted: the reason Facebook is massively popular is because it allows the masses to construct personalized bubbles. If Facebook loses it's "bubbleness" users will simply construct their bubbles on different platforms or in different ways. The space will fracture. You'll have a conservative Facebook clone, a leftist clone, a libertarian one, etc.