cooking during an emergency

Well to start off I thank you for any responses you have. My question is why are rocket stoves such a big thing. Other type cooking devices seem so much simpler and easier, for example the soda can alcohol stove. Rocket stoves seem impractical. For one what I have seen is they need a lot off...

I've head some people talk about these but this is the first video I've seen on how to do it. http://www.wimp.com/coolstove/