The point they (we) are trying to make is that Twitter is a news feed from people you consider interesting. You don't need to know them personally, they don't need to care who you are. Some may be your friends, some may be celebrities.

Maybe all your friends on Facebook are really interesting. Most of us have some old classmate or relative who is a good person but constantly posts inane stuff to Facebook. My Facebook news feed is maybe 30% as interesting as Twitter's. I constantly unfollow boring people on Twitter and replace them by more interesting ones. You can't do that on Facebook.