Philosoraptor

Because it's actually multiple wars. For instance, there was a Civil War of sorts after Episode 6 and before episode 7. (If I remember correctly) The wars may all be 'dark side' vs 'the force' but that's just like saying fights irl are between good and evil.

Separate squabbles/battles*, same main factions. I think your analogy is more like arguing that the 100 Years' War was multiple wars because... reasons.