The goal is to get as much content cached in Cloudflare as possible. This benefits clients by having fast globally distributed websites. This benefits WPengine by having cloudflare take nearly all of the traffic and reduces the origin server resource usage.
However, there are ample opportunities where Wordpress is misconfigured (plugins) or custom code is not correctly configured to set request headers. Those need to be identified and addressed. Most clients have NO insight into what requests are cached or not becuase WPengine's Cloudflare is effectily secret data (except for the dashboard and detailed metric rollups). Cloudflare's API can produce the top 20 urls that were MISS or BYPASS and having that reported means it can be adressed and clients and WPengine benefits.
Having worked with dozend of WP sites, there are misconfigurations due to 3rd party plugins all the time, needlessly wasting hosting resources that could be solved with Cloudflare HIT caching.