The UI isn't pretty and the output format leaves something to be desired, BUT IT WORKS.
Define "works". WotC very likely has requirements that you don't, as I noted upthread. Things like: It needs to work for tens of thousands (if there's calls to non-local storage). Game information must be easily (nigh instantly) updatable with new supplements, *but* that game content information cannot be stored locally in an easily-exported form (for sake of piracy concerns). It must support some form of license verification or login for content updates (that must meet the load and security requiremetns already mentioend. It also has to include mechanisms for programmatic updates and bug fixes as well.
Support for you and support for the D&D community at large are qualitatively different, and that imposes some engineering that you probably haven't had to deal with for yourself.