Because natively with macos you need to use both: 1. cmd+tab to the app you want 2. once on that app you need to use cmd+~ to navigate through the windows of th

Because natively with macos you need to use both: 1. cmd+tab to the app you want 2. once on that app you need to use cmd+~ to navigate through the windows of that app. Alt-Tab allows you to bypass all this and just cmd+tab through all windows of all apps. I find it incredibly useful.