Mild guess. The dev(s) don’t know about navigation buttons. Gestures have been “standard” for a while now so maybe someone forgot about this as a possibility?
Yes. You just swipe left from the edge of the screen to go back. You swipe up from the bottom to go to home. And a smaller swipe from the bottom, dunno how to describe it, for the square menu thingy. Easier than the buttons and you also gain extra screen space.
I don’t care about that small amount of extra screen space, and I don’t like gestures, and I should have the ability to choose which solution I prefer.