I saw a facebook post from a bride telling people... "by now you should've received your wedding invitation. If you haven't and think we liked you enough to invite you then let me know..."
UM. WHAT?!
Then... "please respect MY PLANNING TIME and return your RSVPS ASAP!"
Ok. No. Just No.
Yes people suck and won't RSVP and that is a breach of etiquette but telling people to respect your time on Facebook is in my opinion worse. And basically saying anyone who didn't get an invitation wasn't liked enough.