Then there should be a law that requires the platform to interoperate with independent clients. You can't have both. The social network is a common good. If you want to benefit from it, then you need to treat people fairly.

> The social network is a common good.

Not if it's managed by a company, in which case it's a means to turn a profit. A common good needs to be managed by the community to which it's providing said good, or by an entity that's legally bound to ensure it remains "good" for the community.