> At least right now, that's not true. It's harder to automatically scrape Facebook than a random decentralised system - mainly because decentralised systems need to have the data sharing built in to work. Sharing the data in a structured way is the central idea behind them.

I disagree. It is harder for Joe Average, but for state actors MUCH easier to scrape one system, instead of thousands. Also, it is possible to design decentralized systems in such a way that scraping becomes almost impossible.

> You're not going to be able to block this access from gov only. If known networks become blocked, new gateways can be obtained for less money than is worth mentioning.

You can block based on more than IP address. Decentralized systems can use networks of trust to curtail unwanted information gathering.

> Again, if you're interested in anything resembling a social network, you'll need to share your data with a lot of people. Unless you want to keep it all private - you can do the same thing on FB currently, and border control will not have access to it.

Of course border control has access to it, regardless of your privacy settings. Do you really believe FB has full control over your data?