"Oh good point. Potentially, so also are Dragons and Giants, which is why I implied in one of the many WFRP books I wrote that Dragons, Eagles and Giants were the original inhabitants before the Old Ones arrived - certainly true of Dragons** and Eagles. The myth it appeared in suggested Eagles were of the air, Giants of the land and Dragons of beneath, but anyway, the suggestion was that only the Old Ones creations (elves, dwarves, lizardmen, humans, ogres) were taintable...except for the Halflings, which they got RIGHT after all their other mistakes.
Only problem was, by putting all their effort into making halflings incorruptible, they left them short on everything else. Which is why it is important that, mechanically, they kind of suck. Once you understand WHY they suck, you understand the genius of it all.
**I'm pretty sure the Old Ones LOWERED the world's temp, which is why all the dragons went to sleep - they were cold blooded and couldn't survive without the warmth of the sun."