Perfectionism is a common marker of parenting in an alcoholic, drug-addicted or other dysfunctional family. Realizing this, you should not manipulate and suppress such people.
This can depend on many factors: from personality disorder to the desire to achieve harmony due to certain internal processes, which consists in transforming things. For example, one of the most famous perfectionists was Steve Jobs, who was of dual ethnicity. Having studied his biography, we can conclude that he was a very controversial person, but his desire to achieve the desired result for him led to the development and creation of those products and standards that currently have an abundance of adherents, among whom the mentioned perfectionists also occupy far from the last place, and which we all know today.
Human beliefs. We all come from childhood. We adopt parental models of behavior or put forward demands for ourselves in the course of the wrong upbringing (almost all of us had it wrong). For example, mommy can scold her son for twos and threes, say how bad he is because of this. And since each of us has two basic needs for love and security, the child begins to put forward demands to himself: “I am not worthy of love if I do not receive only fives; I should get only A's, ”this is how the child's beliefs look like. And then they are simply transferred into adulthood and are no longer even realized if you do not consciously work with them. That is, the brain subconsciously saves a person from feelings of deep rejection and dislike by the requirement to himself "I must do everything perfectly, otherwise I am worthless", etc. There may be other options, but the point is that perfectionism is a consequence of distorted attitudes and overestimated exactingness to yourself.