Qaḍāʾ carries several recognized Arabic meanings: deciding a matter, bringing it to completion, giving a ruling, and executing something with determination and precision. The intended sense depends on context; one technical usage should not be imposed on every occurrence of the word.
وَقَضَى رَبُّكَ أَلَّا تَعْبُدُوا إِلَّا إِيَّاهُ
Your Lord has decreed that you worship none but Him. (Qurʾān 17:23)
In this passage, decree includes the meaning of a divine command. It does not imply that every human being has in fact worshipped God alone. The issuing of an obligation and a person's fulfillment of it are distinct events.