Now, those are the extreme cases and it used to be that those were the only cases. Lately, however, it has become a simple case of "this person bothers me and it's not enough to defriend them, I really don't want any contact with them again." Why? Because Facebook and Twitter (I've blocked people there, too, although it doesn't work in quite the same way) are my echo chambers and I don't give a good goddamn what anyone says about that and I have no desire for them to be anything more.
People all too often decry the echo chamber of Facebook and Twitter as a bad thing (in fact, yours truly held out against Facebook and Twitter for a couple of years because my knee-jerking exceeded my reason). You know how it goes: You've got a set of a few hundred people that think like you do and put up all the links to the same things you read and you all agree (to a point) politically and artistically so, horrors, you're not seeing the whole picture. But that's bullshit and here's why.
Politically speaking, I read all the basic news outlets (MSNBC, CNN, New York Times, etc), political blogs from Andrew Sullivan and David Frum to Mother Jones and Politico. I also check out the more extreme sites, like AlterNet or The Drudge Report, Addicting Info or Red State. And at least once every couple of weeks, I even check out the news feed on Conservapedia because, brother, you don't know what a true alternate reality is until you've done that. So while I know where I stand politically, I like to read all the points of view simply because I find it informative to see what the other side thinks and how they got there. But as far as my belief system goes, it doesn't rely on Facebook links for daily growth.
Facebook, to me and for me, is merely a social extension of my likes. As such, I don't want to hang out with people on Facebook who don't share those likes. That would be like having a dinner party and inviting people you couldn't stand. Why go to all that trouble unless you're going to invite actual friends?
So, yes, Facebook is my own personal echo chamber and I'm just fine with that. I go there to relax after working on something and need a break. I go there after I've watched a movie and want to mention it since almost all of my friends are cinephiles, critics and movie bloggers. I go there to put up pictures and make jokes and have fun. And if someone else goes there because they constantly want to decry my belief system or rail against the world I love, fine for them, but I don't want to see it. I see it all the time in the news and I keep up with current events daily. Facebook is where I take it easy and joke around. If the place you slip off your shoes and relax is an echo chamber, I don't see anything wrong with that. Right? Right.
Hear that? I just agreed with myself.