It's just as accurate to say it was fought because Lincoln did not accept the Principles of the Declaration of Independence which articulated the Right of People to leave a government which no longer suited their interest.
The war was fought because Lincoln chose to fight it. Had he chose not to fight it, it wouldn't have been fought.
It is just as accurate to say the war was fought because Davis chose to begin it. Had he chosen not to begin it, it would not have been fought.
If you understand history and the 40 years that lead to the civil war, it would not have been fought if the Fire Eaters had been content to keep their slaves in their own states and not insisted on spreading them everywhere.
Lincoln posed no threat to states rights. Those who thought states rights somehow empowered them to impose their 'peculiar institution' upon the rest of the states, and the nation, against popular will are who caused the war.
BTW. Tell us Sir. What’s the name of that 5th Union Slave state?