In a direct democracy for of government, it is the people who vote and decide upon policy initiatives. There are no elected representatives to act on behalf of the citizens.
It is not possible to practice direct democracy in the present day world with the population of each country running into millions. It is unfeasible that for each of the policies, any country calls for voting from each of its citizens (who qualify the age limit). Policy making with this kind of system will be chaotic, cumbersome and will take a lot of time.