I'm not sure I understand that. You need to customize the export behavior because everyone doesn't prefer the exact same thing. While you prefer not to auto-convert to en/em-dashes, I prefer that. So having options (what you refer to as balkanization) is good.
> Comparisons to the minor incompatibilities of Markdown parsers is laughable
Didn't follow that. What incompatibility is this in reference to? Which parser? Of which flavor of Markdown?
> when the solution to concerns about the format is "customize your local Emacs."
How else would every user get their export behavior unless customizability is added? Taking the same example as yours, I am glad that "--" does the job of "–" or "–".
I know of one Markdown parser (Blackfriday) that adds a similar en-dash/em-dash conversation like Org exporter (and is enabled by default in Hugo). So the customization is needed by a sizeable number of people.
In the end, it's alright if you don't prefer Org mode or like the option to have options. I presented the ox-hugo package for folks who like blogging using Hugo, but don't want the leave the comforts of Org mode. I am not enforcing Org mode on anyone.