It was when Warcraft started. (Even the Scarlets being able to use its power didn’t really cast doubt on that.) The writers have been steadily retconning it over the past few expansions, and I’m pretty sure it’s going to lead to a Babylon 5 rehash.
You can have a good-vs-evil story, or you can have an “all powers are neutral” story, and both can be done well. I feel like they’ve mucked up the emphasis, though, giving us the weaknesses of both types of story and the strengths of neither.