I think what this thread shows is that there are a number of different ways to skin a cat. The riding in or not riding in the drops rule isn't really a rule. It's a suggestion and what their particular paceline is doing. What one should do (if possible) is find out the rules for the group you are riding with before you head out. The clubs that I've ridden with all start rides with a ride leader reviewing the paceline rules.
Where we run into difficulties is when we form into an impromptu paceline on a ride or race. I've had lots of "fun" experiences in those situations. I've had people in front take off, slow down, yoyo, not call out hazards etc., it's just one of the risks you take riding with people you don't know.