There’s no arguing that bottom parts of the screen are easier to reach. However, on Android at least, I find that a view paging with tabs setup is just as effective as bottom navigation bars (since you can swipe from the bottom of the screen to switch between tabs) while keeping that valuable real estate at the bottom of screen free. The whole hide when scrolling thing gets a little distracting. I’d also love if someone came up with a navigation scheme that used Material design’s Floating Buttons or a similar mechanism to provide navigation. They offer the additional advantage of being configurable to show up on whichever side of the screen is better for your dexterity.