It is best that everyone develops equally slowly, little by little so it is realistic development, I'm portraying that Ria even without using her sharingan, she's already strong, she's a Samurai Ninja anyway. Everyone does get stronger but those the likes of Kage, just a little.

Lol I can imagine black market arc, it is a story about illegal stuff, Senju dna being sold in a high cash! XD