Jiang Chen had no reason to conceal information about the ten demonic tribes. In fact, he planned to broadcast their characteristics to the world in order to inform the populace.
He understood the demons better than anyone on Divine Abyss, past or present. Even the ancients, who had a vast wealth of experience personally fighting the demons, didn't know more than he did about their adversaries.
Details about each tribe’s fighting styles, preferences, and special qualities were extremely useful. Knowing the enemy was half the battle, after all.
The demons were perennially successful...