I coulda sworn detonation and pre-ignition were the same thing. They're not! Pre-ignition is ignition of the fresh air/fuel mixture, often started from a single hot point, like a very hot metal burr, or carbon deposits, or spark plug tip. Detonation is a secondary combustion of the remaining air/fuel mixture in the cylinder after normal combustion, from heat and pressure.

Spark advance is necessary because the air/fuel mixture doesn't ignite instantly. With more spark advance, the piston will compress the now-ignited fuel mixture more, leading to a higher chance of secondary combustion (detonation.) The faster the air/fuel can burn, the less spark advance is required, the less chance of a detonation.