No so fast; that's not what I said in my post. I said that if you *wanted* to break cache for (that specific) Accept header, that's how you'd do it.
But please read the thread from this post and below, where @rmccue argues that we *should* be caching JSON requests, and when.
https://aus.social/@rmccue/110020902246277742
Also note that caching some JSON requests are highly desirable, like oembed requests for example.
https://snippets.webaware.com.au/snippets/caching-oembed-with-nginx/