Tapping something is discoverable and a basic human instinct. How the hell do you discover "swipe up from the bottom edge and then slightly right" to open the app switcher?
You don't have to do the slightly right thing, it's just a bit more fluid. If you swipe up and wait a split second before letting go, it also works. There is haptic feedback once the mode triggers. It's fast, but requires intention vs a fluid swipe.