ᐅ Rotary switch on washing machine

In my house, the washing machine is connected to a rotary switch (On / Off). I have seen this several times before but would like to understand why it is done this way.

Is the main purpose to save electricity, or is there another reason for this?

If a device is not powered on, nothing can happen. ..

Thank you!

That used to be common practice 🙂 at least here in Switzerland