What I don't understand about Facebook and Thank yous

You go to an individual’s wall and wish him / her a very Happy Birthday. I equate it to giving the Birthday baby a personal call. Or walking into his / her  home and making a wish. Then why in this world do some folks respond at the end of the day with a very generic, “Thanks to everyone who made my day with your wishes”.

It is like standing in the street and screaming thank you, hoping it reaches everyone that made a wish. In the pre-Facebook era, it was a common bcc mail that thanks everyone in one shot.

When you get a call, you thank them on the phone. When you are wished in person, you thank them on the face. Then why can you not write personal thank you comments when the wish is on your Facebook wall ? When the wish is personal, I cannot figure out why you are so lazy and lethargic to respond with an impersonal broadcast.