Half the people I know on Facebook have changed their displayed name to some combination of their first, last, middle, or other name. They still appear to be 'valid' names, but I reckon they'd get asked to change them if Facebook ever demanded they provide proof of identification.
Not sure what to make of your claim that it's "clear" people "like" Facebook because of this requirement. People put up with it, perhaps, but I know plenty of normal everyday people on FB who aren't really playing by the rules.
The fact that it's clearly possible to use a pseudonym on Facebook makes the German complaint even more silly. But the fact remains that Facebook has decided to have this rule because they believe it makes the product better. That decision is theirs to make, and people can flaunt it (as many do) or decide not to join.
If people going through the hassle of signing up for your service isn't an indication that they like your service, we're all in a lot of trouble here at HN.
They are for sure an indication of initial interest. And given Facebook's retention and engagement rates, I think it's fairly obvious that most people like the service. That's not to say they like the company Facebook, but they obviously like keeping in touch with their friends and family using Facebook's service.
Not sure what to make of your claim that it's "clear" people "like" Facebook because of this requirement. People put up with it, perhaps, but I know plenty of normal everyday people on FB who aren't really playing by the rules.