What we perceive as one of the most useful of memory charms was in fact, in the 18th century, a very daring,not to mention risky, endeavor. There was no limit to the possibilities of the spell going wrong. In the century in question, witches and wizards only used this charm as a last result if all else proved faulty. It just so happened that the Wizard Enforcement agencies of the time were unorganized and sadly, corruption wasrampant among the wizarding community.For a time, the viler of our ancestors would sell to unsuspecting Muggles this memory modifier as a trinket.Once the Muggle touched it, they would fall into a listless coma. Then the wizard would go and steal all of their valuable possessions. It was a terrible exchange, for many innocent Muggles were often blamed for the actions of these terrible witches and wizards. Many Muggle children stories, like the child-preying Baba Yaga,were used as warnings against the supposedly ‘wicked’ wizards that lived amongst Muggles. Remember thatin these times, sorcery and witchcraft were looked upon as workings of the devil.Still, Oblivate was a difficult thing to master. Sometimes the charm would backfire on the owner and result ina complete memory wipe, reducing the aforementioned witch or wizard to a blubbering mass, a baby trapped in an adult’s body. This unfortunate circumstance was all too common in the darker ages of wizarding history.But for the few that had the skills to master this charm, they were hired in masses to the Wizarding Enforcement Agency of their towns. It was then that the wizarding government, the Ministry of Magic,realized the value of having skilled workers in a law enforcement agency. Therefore, it can be logically deduced that the many departments of the Ministry of Magic that we know today stemmed from the lack of useful departments in the 18th century and our tricky little charm: Obliviate.