I stumbled across this while trying to assign a DirectX tag to Trying to Play an Old Game, will Installing Old Direct X Affect Anything?, which is about DirectX in general, as well as DirectX 6 in particular.
What's worse about these tags is that IMO, they have no reason to coexist.
- The tag wikis are nearly identical
- They are not widely used (a total of 17 questions)
- There are probably no experts for DirectX 9 that are not also experts on DirectX 10 and 11 and vice versa, especially in the reduced frame of gaming rather than developing.
The only use for different tags is to use them as descriptors, which is not what tags are supposed to be used for (At a brief glance over the questions in the tags, they seem to mention the exact DirectX version involved in any case, so even this false reason to coexist doesn't apply).
I suggest merging all of these tags into a unified directx. This can be done either by moderator action or by brute force (at the cost of bumping 17 questions).