That's what I've noticed, also. FB has really cut into the cruise meets threads. As soon as someone starts a thread for a specific cruise, someone else (or even the first person) says, "come on over to facebook" and then nothing every happens on the DISboard meet thread.
There are some of us who don't "do" facebook, for various reasons, as well as those who champion how great facebook is.
I wish somehow we could take back our DISboards meets. There's no reason that a cruise couldn't have a facebook group, as well as a DISboard group. But I really find it annoying when a DIS cruise meet thread has a new cruiser post on it, and immediately someone says "we're meeting on facebook".
I, also, have been cut out of participating on at least one cruise because, while the facebook group says "we'll keep you updated" to us over here, it's kind of like being second hand citizens. We have no say in what's being set up or discussed, but we're "invited" to come participate in what they've set up. Not quite as friendly, in my opinion.