Your reasoning is that you know a capacitor is like a tiny battery, and it stores energy... But that an inductor is just wires and can't possibly store energy.
Actually, it can. It is storing it as a magnetic field instead of an electric field.
Just as capacitors resist changes in voltage and will flow as much current as needed to correct that...
... Coils resist changes in current and will flow as much voltage as needed to correct that.
This is why relays have a lower rating for inductive/ballast loads than they do for resistive loads.
So if you're looking for a very high voltage, this is a great setup. Interrupt current flow through the primary coil. The collapsing magnetic field will now drive up voltage on both primary coil and secondary coil, infinitely until current flows, i.e. Until insulation fails somewhere, allowing the current to shunt itself. If you set things up right, that happens at the spark plug.