The reason ninjas were so shunned wasn't because their attacks were particularly powerful. On the contrary, in the Huaxia Martial Arts World, even a high-ranked ninja could be easily crushed by a martial artist at Dark Energy Peak! As for Demigod ninjas, they would face a total rout against an ordinary Grandmaster!
Their strength lay in their ability to become invisible and intangible. If the gap in their power levels wasn't too great, it was extremely difficult for an ordinary Martial Artist to locate a concealed ninja. There was never enough time to see through their concealment. Besides, would a ninja ever grant you the time and space to search for their trail? Absolutely not!
In a battle of one in the open and one in the shadows, even if a ninja's attack power couldn't compare to a Martial Artist of the same rank, their opponent couldn't withstand the constant attrition of sneak attacks.
