The first rule of network security is that your system is insecure. You proceed from there. Sure, but most policy initiatives are not decided by paper ballots.
Direct democracy would probably lead to the wisdom of the crowds coming into play; assuming that people were willing to vote randomly when they knew nothing about the subject. That, I think, is behavior that could be trained into the population.
In a direct democracy situation, real politics comes into play--factional politics. That protects the minority far more than a paper shield like the constitution.
The tyranny of the majority is a largely nonsensical proposal created by a person who felt that government was best organized to protect the opulent minority from market discipline.