That's not entirely accurate. His explanation might have not been substantial but the point was that if you want a dedicated (non usb adapter) power supply, go to your local electronics supplier and pick up a 5V wall wart(not all wal warts are 9v) with attached lead and barrel type jack that will comply with the d2.
Something like:
Edit:
Thing is, p4u kinda did complicate things with the d2's charging port. Pretty much every user will have a micro usb cable and usb adapter(or laptop/pc or tablet) around the house, car or work place and most friends when you visit will as well but with this setup, the cable must accompany the device when traveling unless an external charger is available for the 18650 (or spares).