I know that when the online condolence came into existence, I was not comfortable with the idea of posting to them. With this said, it allows people to post their condolences when maybe they would never get around to sending a card or even know where to send the card.
I enjoyed reading the online comments. They were still just as comforting to me when my beloved mother passed in 1999. And, yes, if it is someone in my "circle", i make a point to snail mail a card vs the online. Or maybe both!
Sandy