Agreed. One only has to board a TGV to see how impossible it is for 100 pax to adhere to basic etiquette at the same time. We simply can't count on it.

That said, the overall noise level in a cabin will make it a significantly lesser problem than in lounges (or trains). 2-3 m away, airplane conversations are already unintelligible. So even if phone calls are not blocked, we don't need 100 pax to behave, but our 20 immediate neighbours. Our chances are not that bad here, so I am not too worried about the inevitable few bad apples. They won't spoil the whole basket.