Because bitcoin is a discovery, all others pow coins are inventions
discovery = decentralized
invention = centralized
That does not make any sense. Discovery means something has already been existing even before you knew it did. For example: gravity. Isaac Newton did not invent gravity but he discovered it. It is an existing concept that he just named and studied.
Bitcoin did not exist before Satoshi. He created it and until now we are still using it. All cryptocurrencies are a product of innovation and invention.