Class segregation is merely skin deep.

Fascism comes from the root word fascia meaning band.

Fascists are the band that groups people together via their aversion to fascist people.

Fascists are a sign of a healthy society in which people are making uninformed decisions and enjoying themselves, if too many fascists gather in a single place then they may form a band that is too restrictive on society at large as it may fail to encompass certain peer humans.

Of course, the end result is the same, but it is a sign of an incredibly unhealthy society to exclude any willing member based on superfascial differences.

In short, the fascists are important to societies, but not because they are a part, but rather because they exist and are excluded.