Expensive doesn't mean "two extra clicks". It means convincing all of your friends and family to use a new platform. Facebook's network effects impose very high switching costs.
That's one reason your "free choice" defense of Facebook is inadequate. Yes, people "choose" to use Facebook. Yes, they are techncially free to stop using it. But, when the cost is high, is the choice really free?
If an individual's social and professional life depends on a platform because that's what everyone else uses, they cannot in practice switch to another platform even if that is their preference. You might as well argue that someone from a disfunctional family gets a new family. Or that someone living in a disfunctional state emigrates. They can do these things in theory, but in practice they are not completely free to do them.