@deborahorodeski I assume Japanese tend to hide who's profile secretly and keep social distance basically. Cos Japan is really small land and island so close each other. I think Japanese tend to get more private isolated space compared with others.
It works dirty especially on the internet to insult,sexual harrasments,crimes. Although simultaneously Japanese don't attack people with exaggerated expressions as it.
With agreement with others, I am giving you another angle from broader view. The country has been isolated & homogeneous society for +300 years, people tend to keep peaceful envirionment with neighbors. They basically don't want to stand out regardless of what it is. They don't like the difference on some areas. Posting a picture will be fun? Of course. We all know but we don't want to stand out. It is an underlying fear that our neighbor will find out my picture one day and say something bad to me. Just a picture with happy face? Sure...but it could be a trouble maker one day becasue I look happy. I would rather avoid that risk.