Why? Because, on the one hand, we insist on "rationality" as the proper measure of human behavior, even when we know that what we define as "rational" cannot be achieved by any human being. On the other hand, those who rule understand this fact and because of it insist on continuing to use "rationality" as the basis upon which to measure humanity and, therefore, find it wanting and unfit to rule themselves.
This is the Double Lie (aka the Double Truth) of "rationality."
This piece from Jared Diamond claims "It's irrational to be religious" can be used to illustrate my point.
For example, Diamond claims:
Virtually all religions hold some supernatural beliefs specific to that religion. That is, a religion’s adherents firmly hold beliefs that conflict with and cannot be confirmed by our experience of the natural world, and that appear implausible to people other than the adherents of that particular religion.By that definition, secular Western philosophy is a religion as it depends upon a definition of human "rationality" that does conflicts with our experience. This is easiest to see in Western orthodox political economy, an applied form of Western philosophy, which is utilitarian in nature and assumes that a rational actor seeks to maximize his economic advantage. This is based on the assumption that "happiness" = "economic advantage." And yet we see people acting against their economic interests all the time, which demonstrates that happiness is something other than economic advantage.
Rather than questioning our model of "rationality" and adjusting it to reflect reality, we blame the poor misguided schmoes for not meeting our unrealistic expectations. It's only one obvious argument from there to deny the masses' ability to rule themselves because they are "incompetent," i.e., irrational.
By his own rules, Diamond is irrational. But the rules are not Diamond's, they belong to Western philosophy, which has been the tool of the rulers for over two thousand years.