We know what happens when the open internet balkanizes into small walled gardens made by big tech companies because we're living through the early stages of it now. They compete for your attention. They try to squeeze every single moment of human life out of you. They will actively encourage bad faith actors to weaponize the web in order to drive engagement and maximize profits. They will do this at the expense of human rights, global health, and civil society. Their engagement maximizing algorithms will contribute ethnic cleansings.
You might find Suler's Psychology of Cyberspace interesting as well as this concept of "Profilicity" developed by Moeller and D'Ambrosio.