I think the problem is that people use Facebook differently, and the rise of online social sites has changed how people define the word "friend."
The people on my friends list are people I truly care about that I either want to stay connected with or reconnect with. If I don't know you or don't want to know you, I am not adding you as a friend. I am agog at people with Facebook friends numbering at 500, 700, over 1,000.
Since Facebook is only for my friends, I don't use my wall to talk about upcoming events. I would consider it rude of me to talk about an activity in front of people who are not invited. I create Secret Events - they can only be seen by the people invited to them - and talk about it there.
For someone that uses Facebook differently, I can see why this might not be true.