[misnome]

> The reason it was marked as dupe was simply because someone took it upon themselves to write up a sprawling smug "canonical" answer to a shitty old question that happened to cover the new subject matter.

This seems an optimistic view. What feels an awful lot of the time it just has some of the same outside appearances, and is a different question completely, but the people marking it as dupe don’t read it carefully enough, or don’t know enough about the subject to realise the differences.