In vim, configuration is either through running commands you could run in normal mode in vim, or through vimscript functions. I assume emacs is similar in that regard.

JSON isn't really that easy to read unless it's pretty formatted, and it's somewhat difficult to write (making sure you have every double-quote, every comma, every closing and opening bracket/brace, etc. I always have to run a JSON linter to make sure I didn't miss anything when writing JSON by hand.