In the pro peloton, I see riders avoiding the pile ups in front of them by riding around them, or on rare occasions, over them (Sagan in some Classic). If the pro just in front goes down, or slams on the brakes, the rider immediately behind is either going around, or is going down. The brakes on the bike in back won't make a difference.
Clearly, there is a separation amount where very different braking performance could be significant. I don't see that the pro peloton is often riding that way. They are too close together to rely on braking to avoid accidents. The ones that don't get caught up are those who maneuver around.