The alternative would be to generate JSON as a JavaScript file or in a SCRIPT tag, so my guess would be so that it can be rendered as part of the view without g

The alternative would be to generate JSON as a JavaScript file or in a SCRIPT tag, so my guess would be so that it can be rendered as part of the view without generating code. Another reason would be that they keep the same HEAD but swap out the BODY for things like a/b testing, caching, page loading, etc. Either way, after you determine that you don't want to store JSON as part of your BODY, the HEAD is the only other place you can store it, and if you don't want to generate code, then META tags probably make the most semantic sense.