That's certainly what Facebook believes. What it doesn't really understand (possibly because its people have gone straight there from college and continued in the same atmosphere) is that normal people want a certain amount of separation between their networks, e.g. work/social/personal.
yeah but...those lines are blurring and not just because of facebook. partially to do with increasing ease of travel and long-distance communication, partially to do with changing attitudes about family maybe? surely there are many other factors, and more still around the bend.
this isn't to say that i don't ever want to say something to my friends but not family, or vice-versa. more often my issues with the "audience" for my facebook posts have to do with various groups interest in the subject of the post - people i went to high school with mostly don't care about python, or some great restaurant out here across the country.