Securing the WP REST API

I think many WordPress users probably underestimate the amount of data that is made available via the REST API. Just about everything is available to anyone or anything that asks for it: posts, pages, categories, tags, comments, taxonomies, media, users, settings, and more. For most of these types of data, public access is useful. For example, if you have a JSON-powered news reader, it can basically replicate your entire site structure virtually anywhere. But that easy access invites potential abuse. Just like with RSS feeds, RESTfully delivered JSON content is easily scraped and used for spam, phishing, plagiarism, adsense, and other foul things.