Social network monopoly

We all know the evil of monopolies. The power created by a monopoly will always be used against its customers, giving them an ever worsening deal. The monopolist will usually maintain there isn't a monopoly situation, while still doing what he can to extend its reach. When disproven he will maintain it's not a bad monopoly, but really a "natural monopoly" and no one is actually getting hurt.
Sooner or later extremely successful companies will be accused of trying to create a monopoly or at least trying to create an oligopoly with others. There are countless examples of this happening and government agencies are working hard to expose the crooks and fine them.
Facebook could be an emerging monopoly. Of course Facebook will behave the same as anyone should they be accused. They might say something like:

• We are not a monopoly. (Always the first defense).
• We're big because people like what we provide. Sorry MySpace!
• People join Facebook, because their friends have done so, and want to keep in touch by being on the same network.
• It's easier for everyone if there's just one social network. It happens to be Facebook. Everybody benefits from our network.
• We provide a platform for third party services. That makes us a vital engine in the economy.
• We do own user data, but the ownership question is unimportant.
• Users don't need to export their data. Where would they go with it and why?
• We only use the data in ways that our users are aware of and accept.
• You can't disconnect a user from Facebook, because the whole network structure would collapse if you did. Most users would not be happy about that.
• We will continue to improve and expand our services.
• At best we provide a lot of people with something they need without charging for it. At worst we're a "natural monopoly".

Of course I googled "Facebook monopoly" before writing this. Top hit was a Monopoly game app for Facebook. Google hits do vary with time. Let's see what the same search gives same time next year.