Last month was the birthday of one of my friends. I opened my Facebook and there it was, people wishing him Happy birthday with all sorts of smileys. Except that he has been dead for one and a half years due to an unfortunate work accident. It was extremely disturbing for me and continued to bother me throughout the day until we got his account memorialised with the help of my friends. Some of the people wishing him appeared closer to him that I was (or at least I thought that way) but never bothered to enquire about his well-being in last 18 months.
No one reads those birthday compliments you write on Facebook, at least no one that I have talked to cares. It is a hassle for some as they reply to or like the posts or just collectively thank them in a post. Some just do not bother.
I have hidden my date of birth on Facebook for last three years. I even experimented with changing to some random date a year before that, it was funny. Now very few people wish me on my birthday. The number decreases each year. Most of them call me or message on Facebook to ask my phone number. This year the number was 7 (that includes my parents and siblings). But it feels great when you know there are few people who care about it(does not mean that people who did not wish do not care, you might simply forget or never bother to find out).
You do not have to be zombies going around writing Happy birthday to everyone, people who you have never talked to or not talked to since years and will not message until their next birthday. If you ever get some free time, find out how they are, what they are doing, do they need any help, are they alive instead of dropping a stupid happy birthday every year on Facebook.