People generally segment their lives. For example you have your work friends, your family friends, your hobby friends. For various people these groups may or may not overlap to varying degrees. Facebook doesn't allow you to segment your friends like most people do in real life, that has consequences for what people say and do and not just in the sense of civility. That's what this article is essentially talking about.
Maybe not on comments, but you can definitely segment your friends on Facebook itself.
If you put your friends into groups, you can click the lock next to the Share button and customize which people or groups get to see the status update.
It's a pain in the ass, but it's definitely possible.
This does not seem to be true. When I click the lock and choose "Customize" I am given a text box in which I can type the names of individual friends, one by one. Groups don't seem to have much -- anything? -- to do with it.
So, yes, you're right, but I'd revise "it's a pain in the ass" to "it's an epic pain in the ass."
