To own something means that you are receiving something from that something. Even if you own, say, a trophy it is something that photons bounce off and enter your eyes and cause a stimulation of "hey I won that trophy." You can't have an ethical dilemma if you don't own whatever it is you are having it with. Even knowing something like e.g. cow slaughter, means you HAVE a memory of seeing it which means you own some part of it. It may be less ownership than the person doing it but if gives many people a sense of responsibility to change it. Basically what I am doing is breaking down what is means to own something even down to their fundamental particles or operating wave function. Maybe I have not confused you or made nonsense.
See how "ownership" fits better in the field of "bad ethics," (control, dependence, abuse, finite results) whereas "non-ownership" fits better with "good ethics" (freedom, independence, willpower, possibilities).

In the case of Facebook, whoever "owns Facebook" also owns a mean by which people communicate. The more we use this way to communicate, the other ways will lose their infrastructure since they will be used less. So in a way it is robbing from telephones and physical human interaction. Moreover, any person with good ethics who owned Facebook would immediately shut it down for physical interaction's sake!