The reason why mukbang gaining such a huge popularity in South Korea is the rise of one person households in Korea. The loneliness and excessive dieting to look slim also encourage people to view such video/broadcast for self satisfaction. Huge percentage of Koreans are on smartphones with easy access to TV streaming capabilities and many are on Seoul subway network during dinner time also contribute for such popularity of mukbang.
The Diva - famous due to pretty looks, slim body and good appetite for good food.
She is like partying alone in front of camera.
Guy eating in front of camera with access to Afreeca TV network.
This is how the mukbang setup look like behind the scene.