gnucash (app-office/gnucash-2.4.11-r1) unable to show help and guide without installed yelp (gnome-extra/yelp), even if gnucash-docs (app-doc/gnucash-docs-2.4.2) installed. This dependency does not exist in its ebuild nor in gnucash-docs ebuild.
Will wait for the rest of the team to decide as this looks like a special case :/
I don't think it's strictly a RDEPEND, otherwise, we would need to add that RDEPEND for every package providing this kind of documentation. In general, if you want to read the docs, install a viewer for them (if you don't want to read plain files with "less", for example)
*** This bug has been marked as a duplicate of bug 340265 ***