Bandwith is shared in a Hub even if only one port of the hub is used (unliked a switch). I mean, if you plug a 1 to 4 port hub, your bandwith is split into 4 despite the number of ports you realy use. So High speed hardware will misperformed or not worked with a hub.
Power supply is a major problem with USB. For exemple some USB modems simply don't work with some PC motherboard because USB controler is known not to be able to supply enough power.
That certainly are the reasons why Apple replyed this way to your mail.
