Comment 46 for bug 19767

A higher priority does not change the fact that Kubuntu does not have the resources, nor does any team member have interest to rewrite KHelpCenter. Same applies for KDE.

Just adding htdig is not the solutions as it was probably stated in some comment above that it is horrible junk, dragging in more horrible junk, not working reliably once it junked it's way through all the docbooks, in case it even manages to do that without falling apart, and even if all that weren't the case it still would not resolve all the other shortcomings, bottlenecks and usability issues that make it the second most awful application in core KDE (kuser being the most awful one).

From my point of view Medium is too high already, since there are much more awkward issues and since this issues is only part of the bigger one that KHC is unmaintained for the better part.
Simply put: KHC needs a rewrite