Question about Icy Box Ib-Ac6104-B

I use a 5 V/2.4 A USB plug-in power supply unit from Apple as the power supply unit.
I connect this to the ICY BOX IB-AC6104-B via the Delock USB2.0 power cable A-5 V, 1.5m, black (83574).

One possibility would be a universal power supply unit. It should have the right plug. It is important that it has an output voltage of 5 V and can supply enough amperes at this voltage. Also remember that higher voltages and thus fast charging are not available. But a quick question: why do you need an extra power supply? Today's USB ports actually supply enough current and hardly any consumers really need much current any more.