Why doesnt a manual transmission go into neutral when the clutch pedal is fully pressed?

When the clutch pedal on a manual transmission vehicle is fully pressed, the clutch plate is disengaged from the flywheel, disconnecting engine power from the wheels. However, the transmission does not automatically go into neutral by itself.

While the clutch pedal is pressed, you can move the gear stick into neutral or any gear. The actual shifting of the gears is done mechanically, and requires you to move the gear lever to put the transmission in the desired gear. So, unless you physically move the gear lever to neutral, the transmission remain in whatever gear it was in before the clutch was pressed.