User blog comment:Bennlimos/HxH Questions & Thoughts Discussion 9/@comment-14902757-20141014171822

I'll answer 1-3 for now. I have yet to come up with good answers for the rest of the Qs. This is only my personal take so...

1) ANS: For some of them like Leorio, the concept of nen may be difficult to grasp at first. Some would probably postpone their nen training specially those who are already content with the license, hence the question. I would say there's only a measly 1-2% of hunters unable to use nen at any given time.

2) ANS: The Greed Island Game also had hunters who are much clumsier. Even if those hunters who attacked Canary were able to learn nen, it's possible they haven't been able to get past mastering the basics. Like Wing said, Gon and Killua are 1 in 10million.

3) ANS: The job came from the Phantom Troupe.