Why?! tl;dr: I get frustrated using writing apps that don’t support Vim style keyboard navigation. If you’re old, nerdy (in a computer sense) or both, you’ve probably come across Vim. It’s great, and there is no denying that keeping one’s fingers on the home row makes one a more efficient inputer. And there’s emacs. It’s great too. This is not an article about Emacs or Vim, but if you’re interested in arcane nerd history, Google: Bram Moolenaar, Richard Stallmand and Eric.
Spacemacs has a hybrid mode where you use vim commands in normal mode and Emacs shortcuts in insert mode. I use that. Or you can turn it completely to Emacs shortcuts.