Because that's literally and exactly the thing it is. Insisting on using a word that does not mean the thing you are talking about instead of a word that does is exactly obscurantism. It's practically definitionally obscurantism.
I get that. There's a real desire to just do hack and slash. And that's fine. But you know what Alignment does in that situation? It raises awkward questions about why you're the literally-and-explicitly Good guys if what you do is practically indistinguishable from violent robbery. If you want to sweep morality under the rug, absolutely the last thing you want to do is throw around Good and Evil (especially in a traditional fantasy setting).A lot of people don't like doing real moral philosophy because it quickly takes them to places they don't want to visit.