Q:

Does the dupe hammer apply to all tags?

I appreciate the dupe hammer but does it apply to every tag? It's reasonable for specific tags like c, java or python but how does it apply for generic tags like image?
Is someone with a gold badge on image an expert in any question, regardless of environment, about images? Is someone with a gold badge on shell an expert on every shell?
With time (and older users still active) someone (if they haven't yet) will get a gold badge for generic tags, will the dupe hammer apply to them too?
I'm not suggesting it must be changed, I just want to know if the  same rule applies regardless of tag type.

A:

The dupe hammer applies to all tags. There's no distinction between a tag that indicates a language, a framework, an algorithm etc...
Rule of thumb: If you're planning to close as a duplicate (dupe hammer available or not), then you should be certain it is indeed a duplicate. 
Example
Let's say you have a gold badge in string (possibly earned from python or ruby or whatever) and you see a question tagged c# string -- this means technically, you could dupe-close the question, but it doesn't mean you should. 
You have one of two choices:

If you're knowledgeable enough about c# (even if you haven't got a gold badge yet) and the context and are sure you know a correct dupe, then yes, you can use your gold badge in string list to wield the hammer. 
Otherwise - leave it be and let the gold badge holders with the main domain expertise deal with it.

