I noticed that the following URL does not come back with any results (I am on the featured tab):
However, mssql is a synonym for sql-server, and the following has results.
The intent is not just to come back with sql-server, but any other mssql variant synonyms (which would be translated into their original tags). I think expanding tag wildcard availability could be an alternate solution for tag hierarchy.
EDIT: Note that https://stackoverflow.com/search?q=mssql* will work, bringing back posts that have references to the original tags and not the synonyms. This just seems to be a bug in certain instances.