The idea of "showing off" with vacations, weekend events or even professional accomplishments seems preposterous to me. How is this socially acceptable is beyond my comprehension.
Likewise, I'm probably only interested in knowing where 10 or so people spent their vacation, and even then, only when the narrative is directed at me or a small number of friends. I can't understand how a public parade of general info and photos can be anything other than utterly shallow and boring.
Needless to say, I don't get Facebook.