The big problem with XHTML2 was that it was designed by people who hated HTML. So they went and made it purposefully incompatible with HTML and XHTML1 in various ways (e.g. tags with the same localName and in the same namespace were supposed to have different behavior).
That made it impossible for a browser to implement both XHTML2 and XHTML1 at once (which was in fact the goal of some of the committee members). And then browsers were faced with the choice of implementing XHTML2 (no content at all out there) or XHTML1+HTML (lots of content out there) but not both, they picked the one you'd expect them to pick...
That made it impossible for a browser to implement both XHTML2 and XHTML1 at once (which was in fact the goal of some of the committee members). And then browsers were faced with the choice of implementing XHTML2 (no content at all out there) or XHTML1+HTML (lots of content out there) but not both, they picked the one you'd expect them to pick...