Not necessarily. Lightning strikes can also cause wildfires.
It's not the spark that is the issue. It's the fact that if these occured naturally they would be small and would burn themselves out over maybe a mile or two.
The problem is that we put out fires so quickly, and do everything we can to stop them, on the west coast that when one finally breaks free it's got WAAAY more flamable material to burn than it should.
Like, immagine you kept piling sticks up in a room. Everyday you put a few more down. If you burned the sticks once a week, the fire would be small and tolerable. If you wait a year, it's gonna burn the whole house down.
That's what happens out west. They keep piling up sticks and they keep putting out the small fires.