Yeah, I know.

EPUB is pretty lax regarding page numbers, it only says in the [SSV](http://www.idpf.org/epub/vocab/structure/#h_pagination):

>  the value of the carrying elements title attribute takes precedence over element content for the purposes of representing the pagebreak value

I agree that the "fallback" of counting elements may not work in some cases, but it's the simplest we can "guess" and has the benefit to "work" with a Content Doc that contains only empty page break marks.

Maybe I should add a warning message though, to warn the user this is guess-work.