Implicit tagging hierarchy
I've seen some references on MSO to the fact that Jeff rejected (supposedly repeatedly) the idea of a tag hierarchy. However, my searching failed to uncover any source material (e.g. actual wording by Jeff/Joel) on the topic.
As a developer, I can see a couple of obvious downsides to having tag hierarchy from the technical standpoint - but as a good developer, I can also see solutions to ameliorate those downsides.
Which leads me to believe that there must have been non-technical (e.g. design, usability, or philosophical) reasons as well. I was wondering if there is any such detail available, or if not, if Jeff or someone else on SO team could be so kind to comment on it?
(In case it is not obvious, I think that tag hierarchy would tremendously help the usability of SO - matter of fact it is one of the only two big improvements of the SO/SE I can think of that would make the site design perfect in my eyes as opposed to just great).
UPDATE: Based on the feedback from this question, I have posted a proposal for tag hierarchy on MSO.