Imagine owning all your social media data that you've created over the years and being able to interact with it on whatever platform you decide.
A single entity will lose the ability to ban or silence you in any way. Instead, moderation and filters will be curated and used by different users and communities to help you follow and find information to your liking.
The data lives everywhere and nowhere at the same time while you control what is private and public with your encryption key.
Built in profit sharing will offer more ways to monetize your content without major corporations eating up all the revenue for work that you've contributed to their network.
This is one of the many usecases of blockchain. Centralized services like Facebook and Twitter will over time become obsolete unless they adopt a more user friendly decentralized model.