I think in the ideal EMS world it may be so. But the current idea of “start” triage and rapid transport simply will not work. In what is known as “refugee” conditions the highest causes of death and disability is trauma followed by public health complications. (dysentery, mal nutrition, etc) Most US EMS providers are not educated nor trained for such conditions. (obviously there are those who are) The mindset is totally different. You cannot focus on one patient, you must be constantly aware of your ever dwindling resources. People with what would seem minor injuries during a normal day will likely succumb to infection. There will be walking, talking people who will ultimately receive no help for the benefit of the most.
During all of this it takes education and training that is simply not part of US EMS at large. Look at uniformed health services, there are nursing spots but not paramedic spots. As you pointed out, there are no hospitals to run to. Transfer to definitive care? The level of definitive is normally reduced. Drop off 200 patients in a parking lot with a handful of doctors and nurses? Hardly helpful. Are these same providers going to independently take care of patients for days or weeks on site?
How about logistical support? Where would these providers stay? Who would be responsible for feeding them? How about hygeine?
FEMA? I Wouldn’t hold my breath waiting for them to help with anything except a post incident investigation of what went wrong. Right now one guy who can hammer boards together to make a hut or purify drinking water or set up a soup kitchen is worth 1000 EMS providers there.
The reason we have a small amount of specific teams is so these people can be trained, equipped and supported while deployed. What about vaccinations? How is it a good idea to turn loose a bunch of wackers from the US in a tropical environment during a disaster? Not everyone is a wacker, but how do you screen for them if you just have open enrollment to go now? How do you ensure their home area isn’t negatively affected when you send them overseas? How do you account for and evacuate them when they figure out their family isn't independantly wealthy enogh to do without their income back home? Planning on paying them for their service? Who is responsible for their health and welfare? What if they are hurt or killed? What if they contract a communicable disease? Under who’s medical direction do they work? Most are certainly not educated enough to be let loose on the world without oversight. Who provides the oversight?
What practical aspect of care are they going to provide? Inoculations? The Military and Uniformed service is more than capable with tremendous experience in the matter. Bleeding control? So what is the next step in bleeding control if you get the bleeding to stop? What are they going to do then? Sit them in line to see a doctor or get evacuated? Why do you need an EMT for that? What about the emotional aspects? Several here have recently stated they would do everything they could to give a kid a chance. In disaster medicine, old, previously ill, and very young are at the bottom of the resources list. Even if they survive the initial event, someday all this international help is going to dry up. They will not be able to survive on their own afterword.
I could write a book on this matter, but the long and short is that while there are Medics and probably a handful of EMTs that could have a positive impact, that number is small, has not already been prescreened, largely without training, experience, or the raw knowledge to improve the situation, not capable of acting without oversight, and brings far too few contributions while being another mouth to feed, water, and a body to account for. Who is providing the PTSD counciling after they get home? Plan on just giving them disability with "thanks and best of luck?"
I'm just saying - while EMTs and Paramedics usually focus on transfer to definitive care, their skills, with some little adaptation, would be applicable to this sort of disaster situation.