Not necessarily. In the past, yogurt was invented by the Mongolians: there was a man, every time he milked out the milk will be left some, he was very anxious about this, once, he forgot to put the milk in a damp place, the next day, he went to see, found that the milk into a kind of thick object, he tasted a mouthful, very good! Then, people from all over the world took to it, and yogurt became popular. Later, the Japanese invented a kind of yogurt powder.

This shows that you don't need a machine to make yogurt, you just need to leave fresh milk for a few days and the yogurt will be ready

.