The change in Kakashi

Wanted notices of the shinobi world.

Under the regulations once signed by every nation and village, once a village declared someone a Missing-nin, that ninja no longer had any connection to their home Shinobi Village, regardless of their previous achievements or reputation.

Powerful ninja naturally possessed combat abilities far beyond those of ordinary people, making them far too dangerous for any group seeking peace. Besides, plenty of people had never been willing to behave themselves, and every village knew it.

Espionage, murder, even subversion and rebellion were nothing new in the shinobi world. Every village had seen them time and again.

So, for a shinobi world that sought stability at least on the surface, the Missing-nin system had received virtually unanimous approval from the villages when it was proposed, and they had agreed to abide by it.

Simply put, if someone did something that harmed their village's interests—or the village believed they had—the village would weigh the pros and cons, then announce their name to the shinobi world as a Missing-nin, publicly severing ties with them.

The other Shinobi Villages receiving the news would then accept that whatever this Missing-nin did afterward had nothing to do with their former village.

After all, to put it bluntly, every family had its troublemakers. Ninja lived with their lives on the line, so it was perfectly normal for them to want to gain something through their own strength.

If someone still held a village responsible for a ninja's actions after it issued a Missing-nin notice, then settling the accounts for every Missing-nin's deeds would leave every village mired in trouble. They might as well recognize it as a shared regulation instead. That was why the Missing-nin system existed.

A large portion of each village's Anbu missions involved hunting down their own village's traitors