Addiction is a complex subject. Personally, I think FB/Social engagement is habituation, but if somebody shows me there is a persisting dopamine/oxy rush, and its affecting neurotransmitters such that when you don't do it, you feel down, I might change my mind.

"addiction" is this decades "Schizophrenia" or "bipolar" being misapplied, when it has specific meaning.

I should of course add, not a doctor, not a clinical psychologist. Maybe habituation and addiction are closer than I think.