Cryptocurrency world is unlimited while Fiat currency world limited many things.
Fiat money became something crucial for the whole world by a decision of a USA President stop exchanging gold to dollar.
And at that time you were she was the country with most gold so they decided to print the certificate of good which is now today's dollar. so anyone have the dollar already have good but the number of dollar already more than the numbers all go to stored so did US President stopped changing gold to dollar.