I think the best way to learn the culture of another country is inside-looking out! To coomunicate, to meet many interesting people, to share your emotions and impressions - what can be more exciting in traveling?:) I am sure that when hosts talk to the serfers, they can feel everyday life of this country, and the serfers can get invaluable experience of communicating with foreigners, and to be inspired by their stories on new journeys to others countries! And of course it's a great chance to make friends and acquaintances. Who knows, maybe my good friends live in another country and I have even haven't known them;)