There is a new thread in the General forum on WebBook:
https://www.mobileread.com/forums/sh...78#post3685378
Many of you frequently complain about priorities of EPUB spec evolution and the strangeness of many parts of the spec, both requirements and things unspecified.
The WebBook spec is a github project. Maybe they are more open to suggestions.
It is starting out with EPUB compatibility, so maybe it has a chance to get started.