ESI is awesome and really connects "let's just cache it" with "but what if this tiny detail in the footer changes and we'll spent hours refreshing the cache". I

ESI is awesome and really connects "let's just cache it" with "but what if this tiny detail in the footer changes and we'll spent hours refreshing the cache". I would've loved to do more with it, but we added a lot more optimization that need to happen before the cache and require access to the whole page, so now I do a poor man's ESI transparently caching all kinds of widgets and shortcodes (Frankenstein's WP). I guess one could potentially have tiered caches with an optimization layer in the middle and ESI on the backend-facing cache, but that feels extreme and more brittle.