People do not support football teams by comparing the stats of every single player to decide which team has the highest chances of winning. They are irrational.
However, they do compare stats when they are picking players for their fantasy team; they might not even pick anyone from the team they support. They are rational.
Similarly, voters do not support candidates by comparing the manifesto of every single candidate. They are irrational.
However, they do compare manifestos when the project they are working on is influenced by the elected candidate. They are rational.
Personal interest dictates who stays irrational and who doesn’t.
The flaw in democracy is that not everyone carries a personal interest in what happens on the ground economically. If everyone did, democracy would have been ideal for a country’s growth.