The reason for this is that Durkheim believes that deviance is actually necessary for a society. The presence of deviants within a society allows the society to pull together and feel more solidarity as it responds to those who would violate its norms.
To Durkheim, deviant behavior forces us to redefine and reaffirm who we are as a society. By seeing what it looks like when people act wrongly, we can be more certain of what right behavior is. When deviant behavior exists, it makes our moral boundaries clearer and gives us a better understanding of what is acceptable and what is not. In addition, our responses to deviant behavior draw us closer together as a society. We feel more of a bond with one another because we have a common enemy in the deviants.
For these reasons, deviance and deviants are important to the cohesiveness of our society. Therefore, if they did not exist (one can argue) we would have to create them.