Well, THIS would be magic because it is not the way how it works
The input is connected 1:1 to all outputs so in the end it does not work different to a y-adapter. The only special thing here is that with the jumper you can disconnect the rpm signal pin from all outputs but the first one. With all rpm signal pins connected you would get no useful signal. While it makes no sense for fans to have all pins connected, it is great for the aquabus because it requires all pins on all ports.