Except any of them who actually take up those powers would be exiled, or FAR more likely, executed. They have zero tolerance for fel magics and their culture has been this way for a LONG time, ever since they left Argus.
Seriously. Night elven demon hunters are already banished from their culture and shunned by everyone because of about 10,000 years of knowing demons are bad and two invasions of the Burning Legion. Draenei have over twice that period of time knowing such and are the minor remnants of their once-pure race who was corrupted into becoming some of the strongest parts of the Burning Legion.
If night elves just banish demon hunters, what do you think a race whose sole purpose is the eradication of demons would do?