Let me start by saying that I agree with you on the whole and with most particulars. Being a contrarian, however, please indulge me in my attempt to steelman an opposing view; the ancient fascination with the Noble Lie.

It's present as far back as Plato's Republic; the idea that an accurate communication of truth is not ideal for the preservation of a society. Rather, he advocated for the guardians and rulers of the city - and, let us not forget, therefore the conscious mind in his allegory - be taught untruth. That their nature is such-and-such, and therefore society is the way that it is. Obviously to modern sensibilities, the actual content of the lie that he proposes, and the society he describes, are abhorrent, but the idea that falsehood is more useful in binding a group together than truth remains poignant.

The Noble Lie underpins our ideas of the values of myths, legends, and even shared culture ("If you want to build a boat, don't drum up the men to gather wood, divide the work, and give orders. Instead, teach them to yearn for the vast and endless sea."). In modern times, in comes in the form of the American Dream, of the idea that a superorganism like a government or non-profit or corporation could "stand" for any values conceivable or desirable by the mere humans that make them up. It is the grease in the gears that allow modern developed societies to function as efficiently as they do. For example, to believe that it is abnormal, unusual, even evil to be corrupt is to bind oneself tightly to more proper behavior. As one learns more of widespread and open corruption, it becomes easier to justify taking part oneself, until one's pulchritude turns from admirable moral steadfastness to comical adherence to obsoleted ideals. The breakdown of social order begins with the dissolution of the lies that bind people together past Dunbar's Number, into a collective that believes, even if faintly and insincerely, that each other member is as deserving of happiness and success as they.

I propose that if people believe that their society is fair, just, and truthful, they will act as if it were so, and the good among them make it so. Those inclined to their own good above the good of their kin and kindred will, of course, be able to abuse such trust to great advantage, requiring controls as you've pointed out to identify such proclivities and deter the individuals or contain their damage. Mark that; it is a failing of a high-trust society (such as America's) that they are vulnerable to psychopaths.

In this, we find the argument for allowing leaders to lie to their people. To tell the unvarnished truth rips away the polite lie that society works for their benefit and in so doing makes the most extreme failures of that mode possible. It makes fools of honest people by exposing how foolish honesty can be. Lie, and say that soldiers will never be forgotten, their sacrifices necessary. Lie, and say that your vote and voice matter, that your citizenship carries sacred duties. Lie, and say that the moral arc of your culture is righteous, and that in the end all shall receive their just rewards. Lie, and allow the world to spin one day longer. And I can see the counterargument that this is equivalent to dealing with a rotting foundation by painting over the cracks and the mold and claiming that everything is fine, of standing in the burning room and denying the heat. I disagree with that assessment.

Humans have the ability to become as they aspire to be. Surround a man with fools and it will not take long for him to begin to act foolishly to fit in with his peers. Take that same man and give him the company of the wise, and he will strive to become like them. The same is true for societies. Humans take more notice of their losses than their gains. They pay more attention to threats and insults than gifts and compliments. Tell a man of his 99 admirable qualities and one deficiency, and see which statement he remembers better! By this failure we see the problem of the strict truth; the quickest, surest path to individual success is, most often, one that betrays the ideals of your society. Unable to disguise that fact, the intelligent soon realize that honor, justice, equality, and all other good and noble things your society strives for are chains that bind them to failure. When all realize this, society is lost.