Not strictly true - I play on a proper server and have needed to manually patch on two occasions
First was when Blizzard borked the background downloader so that it didn't recognise the most recent patch.
Second was when I moved house and didn't have my broadband up yet. Playing WoW on dialup actually works very well, but downloading a 500+mb patch is no fun, so I downloaded the patch manually at work and applied it at home.
Blizzard do provide a link to the manual patches from their support page, but I am at work so I couldn't access it to provide a link to the OP.
Anyway, ignoring all that, aren't we on patch 2.1.3 now? Maybe he is on a private server after all
Some people have firewall problems with the Blizz downloader, or sometimes it's just plain too slow (for those of us with high speed connections that are really impatient ). Additionally, the Blizz downloader has no ability to cap upload, which on one hand is good, but on the other it KILLS your whole connection by using ALL of the upsteam bandwidth. Not good at all. It's possible to extract the torrent file from the downloader and use a proper torrent client though.