Why does taking mediators in worshiping the Creator lead to eternity in Hellfire?

It is known, according to the human laws, that violating the rights of the king or the one in charge does not stand on an equal footing with other crimes. So, what about the King of all kings?! The right of Allah Almighty upon His slaves is to be worshiped alone, as the Prophet (may Allah's peace and blessings be upon him) said: "Allah's right upon His servants is that they should worship Him and associate no partners with Him...Do you know what is the servants' right upon Allah if they do so?" I said: "Allah and His Messenger know best." He said: "The right of the servants upon Allah is that He should not punish them."

It is enough to imagine giving someone a gift and that person thanks and praises someone else for that gift. Bearing in mind that Allah has the highest attributes, this is how the slaves deal with their Creator; He has granted them limitless blessings, but they show gratitude to others and the Creator after all does not need them.