A spec being draft seems like an odd reason to ignore it and do a completely different API. Intersection Observer has been implemented in Chrome since 51, and

A spec being draft seems like an odd reason to ignore it and do a completely different API. Intersection Observer has been implemented in Chrome since 51, and Opera since 38. It's currently being implemented in Firefox ( https://bugzilla.mozilla.org/show_bug.cgi?id=1243846 https://bugzilla.mozilla.org/show_bug.cgi?id=1243846 ), and is "likely" from Edge (https://developer.microsoft.com/en-us/microsoft-edge/platform/status/intersectionobserver/ https://developer.microsoft.com/en-us/microsoft-edge/platfor... ). in-view.js's API is certainly less likely to be the cross-platform API than Intersection Observer. Also, plenty of APIs are implemented by browsers at the editor's draft stage.