> That said, they're of course still enforcing their real name policy and so your general point still stands.

Last time I checked (2013?), not in Germany. Germans are allowed to use any (nick)name.

Verifying your login by asking for mobile phone in many cases. Put captcha before login are all means to identify a person indirectly.

I have not yet tried it in EU, but for rest of the world, Facebook and other services do it very often. They precisely want to know your location by some means and when they cannot a dreaded verification process starts.