We've had the tag length character limit extended to 35 - that's great! This announcement has prompted an effort to rename old tags that have been shortened due to this limitation - and dada has been successfully renamed to defence-against-the-dark-arts. Awesome.
But why do we have that tag in the first place? From a glance at the questions (28 total), I see that some of them are about the teaching position, and the people who occupied it; some are about Voldemort cursing it; the rest are a mixed bunch, and some I believe don't even need it.
Here's what I think: the position itself isn't a prominent topic in the franchise. If we're going to use the tag to refer to all DADA teachers, then it's too ambiguous. If we're going to refer to DADA as a lesson, then it's no use either because it's too fine-grained. One cannot be expected to focus on this lesson only.
(There's also the argument about the correct spelling - is it "defence, the British spelling, or "defense, the American spelling? the author is British, but the official stance here seems to be to use American spellings (though we don't have sorcerers-stone, thank god). If both are to be synonyms, which should be the main tag?)
I say we don't need this tag. Should we burninate it?