As if there is no way to distinguish fighting for position and actively blocking the road at a low speed.
And I mean yeah, as you wrote, the question is by what means riders are allowed to defend their position. I just think blocking the entire width of the road with your team is clearly a step too far.
My point is to zoom in on that. When a whole team block the front, what is it that an individual rider of that team does? And what should he be allowed to do?
Whether an action is done only by a single rider or coordinated with multiple teams, the same behaviour should be allowed.
Should a rider be allowed to go slowly? Yes. Thus too a whole team to go slowly (as long as you don't endanger others, see lead-out riders in a sprint for a good example of that).
Should a rider be allowed to lean against another rider, if it is done to stay in place? Yes. Thus too for a whole team.
Etc.
Of course, sometimes we see riders try to block the road by what is otherwise abnormal behaviour. We've seen reckless sudden movements to the side, and use of elbows in a way that would get you relegated in a sprint. I'm all for making a distinction between blocking the road safely and unsafely, and to penalise dangerous behaviour. But I disfavour regulations against coordination.