There has never been a Western philosopher who wasn't hyperbolic about something, and there probably never will be, considering that European philosophers operate in a materialistic culture, that demands its thinkers make moral and physical truth into something as literally true as the wall in front of your face. For Sarte the inevitable hyperbole comes in his idea of total freedom, to the point where even a biological human nature is illusory.
At the opposite and equally wrong extreme is the idea that human nature is uniform, that every person ever alive desires the same things: sex, material wealth, power over his environment and other human beings. These are the things that all societies are built on, and self-styled revolutionaries act only out of spite for what they can't have or as a backhanded means of taking what everyone wants.
I myself think that there is some biological element of human personality, but I still hold to the idea that existence proceeds essence. The only universal desire is desire itself. Biological imperatives filtered through a conscious human brain produce so many different desires that it hardly matters if they come from the same impulse or not. It just isn't true that everybody wants as much sex and dominance as they can possibly get, and that anyone who claims to be relatively unconcerned by these things is a capricious lying weasel. There are many who are moved more by their internal dialogues then their interactions with others, and for us the thing is simply to desire something, to have something to want and work for and measure the passage of time with.
But there is a terrible loneliness that comes with the realization that we are creatures of ourselves, that there is no common essence that can possibly be created through blood, religion, language, sex, or anything else, and so there can be no common experiences, no objective perceptions. The most intimate moments between the closest people must pass through minds wholly unconnected to each other.
It is no surprise that existentialism and religious skepticism have thrived in a Europe that has suffered epically to maintain the illusion of common essence,and gave it up only when it absolutely had to for its own survival. The United States has faced no such choice. There has been no inquisition here, the World Wars and the ethnic/religious mythologies that produced them are nothing but abstractions to every American who wasn't unlucky enough to be a man of eighteen to thirty during the wars. We have had our Pogroms in the form of savage anti-black race riots, but we don't hear about those very often, not as much as we hear about the evils of the Godless Communist and the fanatical Muslim, not as often as we are told that being American is inoculation from the worst elements of being human.
No, this is the land of the achiever and the eternal optimist, a land that demands a moral code that is simple and light. And so there is the American idea of liberty, one based on the idea of a universal human nature and universal desires. One that offers influence over society in the form of tangible corporate pyramids, surrogate penii in the form of a house or an automobile or a rifle or (just about anything else you could think of really) Most of all American liberty is expressed through desire for tangible things: big car, big yard, big dog, brass ring.
So those American artists and thinkers who have stared into the void and taken it for what it is tend towards nihilism of the harshest and most relentless kind. The bitterness of a jilted lovers, rejected by a universe they thought was made for them. There is no Camus among us extolling the happiness that comes with futile mortal striving. Instead we have Stephen Crane making comrades with devils and Mark Twain rejecting any redeeming feature of being human with increasing vehemence. Poisonous anger, outrageous self-abuse, and general embrace of death are the usual traits for the American who rejects common essence.
A close parallel to contemporary American society can be found in Dostoevsky's Tsarist Russia; boisterous, ambitious, self-assured, and more then a little full of shit. Empires cannot function without the illusion of common essence and the mythology of superior essence that springs from it. Nor can illusions of common essence cannot possibly survive the vast sampling of humanity available to people who live in empires.
Americans have historically tried to solve this problem by embracing either lies or death or both. It hasn't worked, and it's not going to, and the Joy of Futile Striving Party doesn't look like its going to be winning any votes anytime soon.