For the benefit of others who don't understand the essence of tuning, going back to the basics of Intake, Compression, Power and Exhaust strokes of the engine cycle is best to start understanding.

In the case of advancing ignition timing, imagine the piston moving up n down in the engine. Advancing timing will cause the combustion/power stroke to begin earlier, which in this scenario, imagine the piston not fully finishing its upwards motion, and the plug fires and burn fuel which then pushes the piston quickly downwards. This will lead to increased stress on the pistons and rings, which would then lead to detonation and damage if timing is advanced too much.