Something from the webdev zeitgeist that gets me is the notion that its somehow more efficient for servers to convert their data into JSON rather than HTML.
In either case all this really involves is concatenating strings, remembering to escape them (Hopefully you're aided by a good templating language!) where needed!
Webdevs have taken to calling outputting HTML "rendering" to imply that its more complex than it really is. Come on, rendering is what the browser does!