Had this happen to me as well half an hour ago. BRD legs dropped, but I was typing in order to say thanks to the alliance for the smooth run. It only took 10 seconds for everyone from my party to leave and I got saddled up with an item I don't need nor want (I have the AF+1 already) and a week of waiting until I can loot something I'm actually interested in (BRD feet or MNK set).
While this has always been the case, never has it had consequences like in CT where you're locked out for a whole week. I do agree not rolling for five minutes should have some kind of penalty, but even then I've had times where, after running WP for the 10th time, I didn't even look at the loot button anymore and just forgot about it, so mistakes can still happen even in that case.
I'm not gonna propose a solution because I don't have one, but something clearly needs to be done about the looting when everyone left thing.