I've got to agree with Greenbean about careless divers damaging reefs. I have a feeling a healthy percentage of divers are careful, but there are plenty who aren't. I've personally witnessed such carnage down in the Keys and a lesser extent in Coz. Not pretty, and sad.
Avoiding politics, we do know that isolated or off-limits reefs are doing much better. If we want healthier reefs, it appears that we're going to have to reduce our activity in and around them. Is there such a thing as sustainable diving?
I will say that sovereign nations likely have the right and authority to govern access to the reefs in their territorial waters. So, if the Mexicans, Dominicans or whoever want to let their reefs get dived out, that is their choice to make. Is anyone aware of any international treaties related to reefs?