Wait, so this would only happen to people who's gods frown on Cannibalism right? Because elves would be in trouble otherwise. Of course, this could always lead to some amusing problems with worldgen if an elf society somehow winds up worshipping an anti-cannibalism god (Perhaps they could adopt worshipping that god from the humans, gobbos or dwarves by being conquered, or migration, there's plenty of ways it could conceivably happen in worldgen) they would be fucked. Like, they'd all get cursed and turned into Wendigos. At that point, would they even become monsters who prey on towns and live in lairs? If they're ALL turned into horrible abominations, and ALL already liked eating dead sentient things, why would they care? They'd continue go about business as usual, but now they're wendigos.
Edit: I don't watch Star-Trek, but I once read that Something similar happened in The Next Generation: Now, in the Patrick Stewart-era of Star Trek they actually had a big budget for costumes and such, while back in the Shatner-era the show was broke and the set and wardrobe guys had to cannibalize old props, costumes and sets from the studios (hence, "ooh look, a WWII/Ancient Rome/Gangster planet!"). So while originally Klingon's were just guys with waxed eyebrows and bad sunburn, in TNG they all had the ridged foreheads and crap. So anyways, apparently instead of just ignoring it/retconning their appearance, in one episode of TNG they reveal that between the series', some Horrible Thing happened that spontaneously mutated the foreheads of every single Klingon anywhere. While they were quite distressed by this, the Klingon's just kept on Klingin', and it was only never brought up before because it's still a painful topic or something.