Depends on how it is structured? I mean, Reavers are a cool example, but I have no clue how they have managed to last as long as they have while being completely insane. Warcraft Orcs made pacts with demons, but I don't know how deeply that extended, and obviously they broke out of that.
Reavers existing for decades only makes sense if you squint but then again this is a universe where they have cool western train robberies in space so I don't hold up the lens TOO close. They fulfill the role of 'ravening horde' narratively for the story, as well as acting as a mystery plot hook and an interesting reveal...and a bit of a dues ex machina at one point too in the Serenity movie.
Reavers, an all bad cannot be reasoned with shoot on sight group, makes for a very interesting story element. A key one, even!
I dunno too much about warcraft lore. But they do got the whole shamanistic vibe goin on, hard, from what I've seen anyway.