People vote mostly of out self interest, but mediating their expression of self interest through elected representatives enables pragmatic compromises that make the most good for the most people. Ultimately, I view representative democracy as a recognition that the political process will always depend on a small number of powerful people, so it's better if those people have some accountability to the people. Direct democracy circumvents that political process, forcing representatives' hands and blocking compromise. The result is stuff like Brexit.
I do think there is a place for direct democracy, but it is very limited. Historically it has been useful in affecting constitutional change e.g. the 1967 Australian referendum to grant citizenship to Aboriginals.
Interesting mental exercises aside, this article is hard to take seriously.