It would be impossible to keep the capacitor's voltage constant. Each time you close the switch you'll dump a voltage (what voltage?) on it, and the voltage would go up due to a high current peak. The capacitor wouldn't like it either. And you'll lose lots of energy in the switching.

In a switcher the coil makes that the current charging the capacitor rises smoothly and that on average it follows the load current. The diode is needed for when the switch opens. At that moment the coil has built up a magnetic field whose energy has to go somewhere. The diode closes the loop that allows the coil's current to remain flowing.

Thanks to more advanced switching devices buck converters are much simpler to build these days than their operation theory would suggest. And they can achieve up to 95% efficiency, which just switching a capacitor on and off never can do.

It would be impossible to keep the capacitor's voltage constant. Each time you close the switch you'll dump a voltage (what voltage?) on it, and the voltage would go up due to a high current peak. The capacitor wouldn't like it either. And you'll lose lots of energy in the switching.

In a switcher the coil makes that the current charging the capacitor rises smoothly and that on average it follows the load current. The diode is needed for when the switch opens. At that moment the coil has built up a magnetic field whose energy has to go somewhere. The diode closes the loop that allows the coil's current to remain flowing.

Thanks to more advanced switching devices buck converters are much simpler to build these days than their operation theory would suggest. And they can achieve up to 95% efficiency, which just switching a capacitor on and off never can do.

It would be impossible to keep the capacitor's voltage constant. Each time you close the switch you'll dump a voltage (what voltage?) on it, and the voltage would go up due to a high current peak. The capacitor wouldn't like it either. And you'll lose lots of energy in the switching.

In a switcher the coil makes that the current charging the capacitor rises smoothly and that on average it follows the load current. The diode is needed for when the switch opens. At that moment the coil has built up a magnetic field whose energy has to go somewhere. The diode closes the loop that allows the coil's current to remain flowing.

Thanks to more advanced switching devices buck converters are much simpler to build these days than their operation theory would suggest. And they can achieve up to 95% efficiency, which just switching a capacitor on and off never can do.

It would be impossible to keep the capacitor's voltage constant. Each time you close the switch you'll dump a voltage (what voltage?) on it, and the voltage would go up due to a high current peak. The capacitor wouldn't like it either. And you'll lose lots of energy in the switching.

In a switcher the coil makes that the current charging the capacitor rises smoothly and that on average it follows the load current. The diode is needed for when the switch opens. At that moment the coil has built up a magnetic field whose energy has to go somewhere. The diode closes the loop that allows the coil's current to remain flowing.

Thanks to more advanced switching devices buck converters are much simpler to build these days than their operation theory would suggest. And they can achieve up to 95% efficiency, which just switching a capacitor on and off never can do.