Considering the armed attackers have guns themselves and not every shot you make is going to be a cool john wick™ shot through their eye, they may take multiple rounds and you may miss one while they’re shooting back at you, yeah that’s exactly when you need standard capacity magazines.
What, do you think this is for people shooting a bunch of unarmed pedestrians in a tight space with poor egress paths? Magazines are quick to reload if you aren’t being actively shot at, it’s trivial for them to “press button, grab other mag from wherever it was staged, slap in, charge round, and go” takes about 2sec if you’re untrained, fraction of a second if you practiced in your room for a month with your gear and these fuckfaces plan their shit for months, they have the time. Look up a couple videos on reloading anything with a detachable magazine, mag bans are meaningless.