Only an abject idiot believes that all people are equal.
Humans do not clone. They mix genes when they reproduce, and they mix phenotypes as these genes are activated. Some people are born with certain genetic traits that affect their proneness to hair color, voice pitch, or whether a limb develops healthily or withers and dies. And some genes influence diseases. CJD. Failure of certain organs. Schizophrenia. And, most importantly, personality traits.
And in the same way you can be born with a shriveled limb, you can break your limb in your life experiences. Similarly, just as some personalities are created damaged or prone to damage, personalities can receive damage. Some damage to personality cannot be corrected.
And in the same way we do not expect a crippled man to climb a staircase, we do not expect someone with the personality type of an athlete to develop the first antimatter warhead in his basement. We can't expect an ESTP to behave like an INFP, or an ILE like ann ILI. Or an Enneagram 3 like an Enneagram 8.
No matter how much effort you put into a work, an ESFP in his prime will never be able to outperform an INFJ in his prime at an INFJ trade or skill. An Si-user cannot sustainably live an Se-favoring lifestyle. You will always be limited to the confines of your personality type.
At the same time, a Te-user cannot expect to succeed in even a Te-field if he depends solely on his talent while letting his effort falter. He may continue to outperform a slacking Ti-user in a Te-field, or even a striving, dedicated Fe-user in a Te-field, but there will always be other striving Te-users in this field putting in more effort and moving up past you.
So, whether cognitive functions are inborn or acquired, a person with an unfavorable, relatively useless cognitive function must still be expected to work as hard as one with a more useful cognitive function. He is a servant in the social structure, he will always be a servant, his greatest talents are in being a servant, and he will meet with destruction if he tries to be anything but a servant. He must learn to accept the fact that he is inferior.
And a person with a powerful function will still need to perform, or he will fall just as quickly.
So, the true danger involved in typology is that 1) the learner of typology will blame his failures on his functions, and give up, because his personality type is that of the servant, not the ruler, or 2) the learner of typology will fall to narcissism, he will deprive himself of future successes because he chooses to reap the moderate rewards of a useful cognitive function he uses indolently, rather than using it to its greatest potential and making the greatest contribution he possibly can.
However, while knowledge of bleak truth can lead to nihilism, it's often your only way to avoid destruction.
You will never learn your full potential without understanding typology. You will realize your weaknesses and your strengths, however much you hate them, but they are all you have to use. You must face your fears. You must realize you are worthless, you must realize you are a peon, you must realize that you are everything that you say you hate, and you must realize that you will always be a slave to your fears, as all good little animals are.
If you ignore the bleak truth revealed by typology, you will never understand why or how you failed in the past, and you will never get the fullest extent of an answer, you will never have a plan to rise and succeed. Know yourself, otherwise you will lose most of the battles you enter. Deny it all you want, but you are this type, you have the strengths and weaknesses of this type, it will affect everything you do, and it will be with you all your life.
Swallow your pride. You're worthless, no one loves you, you were born to be a mindless zombie slave and you're going to like it.