Why is direct democracy not used anymore?

Democraticcountry's are the result of wealth slowly making its way to the general public. This and the economic system that came as the result of the industrial revolution led to a system of education and knowledge where first the nobility and then the religious institutions were striped of their power. Most of the country's in the world that are not democracy's don't even understand what the term entails, they are ruled by corrupt religious and military centers of self interest that depend on the metaphysical reasoning of religion and or the reasoning of simple brute force. It will still take some time before these tenets become a thing of the past. The short answer is, They were not lucky enough to have gone through the industrial revolution without the hind sight of history.