What's with miniguns in some video games needing their rotary to spin for a moment before shooting?

Like it needs to gain momentum before it's capable of firing, which is not a thing irl. Like any firearm, miniguns fire the moment you pull the trigger (or whatever is the equivalent on miniguns.) I don't even see what the point of making it so the rotary has to get spinning first before it can fire. Because it's supposed to look more menacing? A balancing thing so those on the business end have time to react? Idk, but it's ridiculous.