I wonder. Maybe it is annoying for some people to see birthday notices of people they don't know.... (for my part, it never bothers me to see birthday greets for people I don't know)
We need markers to take stock of where we are, what we have achieved, if anything, and where we want to go from there. All of those (New Year, birthdays, anniversaries, etc) are of course artificial. That doesn't make them any less real or important for the person concerned...
