Measuring the utility of WP_REST_Posts_Controller

A good measure of the utility of WP_REST_Posts_Controller and brethren would be to test how much (or little) time it takes for a developer to correctly model their custom post type data by extending it. If it’s easy to do, then we’ve established a great abstraction. If there are pain points or places we need to work around, then we should refine the abstraction.