There was software such as PCKeyboardHack/Karabiner and something else before that that let you do remappings not available through Keyboard Preferences. Every Mac OS X release breaks keyboard internals and things like PCKeyboardHack stop working (Sierra was out for almost a year before Karabiner Elements was fully functional). Mac OS X support for custom keyboard layouts is atrocious, and IMO Macbook keyboards are garbage compared to shaped (models up to x220/t420) Thinkpad keyboards. If you look around at some of the different keyboard layouts and try some remappings out what you will probably find is that remapping Caps Lock to Backspace is the best for general typing (this started with the MIT AI Lab's "Knight TV" terminals designed by Tom Knight). I haven't tried it but this should be possible with Karabiner Elements in Sierra now.
