I´m starting to wonder if the whole Hunter-organization has some deeper connection to the Chimera-monsters. Like, they´re undeniably a global threat. And if there was a previous queen that ate human beings, chances are it was nen-users that defeated that previous queen. Considering their strength, only an experienced nen-user would stand a chance against these monsters. Who knows, seeing him in the opening, maybe Netero was the one who defeated the previous Chimera-queen/king?

Since the Chimera could appear anywhere on earth, having hunters everywhere "hunting" stuff would come in pretty handy.

Well, that´s maybe all pure fanfiction on my part, but I like the thought