I think we are talking past each other on this one. Of course I know that many AVRs and other components, including my Denons feature RS-232. So in the sense that it is in active use, RS-232 is certainly not obsolete.
However, my claim is that RS-232 as protocol for newly built equipment, has been obsolete for a quarter century, and any manufacturer that continues to use it is . At bare, bare minimum they should be using USB, but really they should be using WiFi or at least Ethernet. To be building equipment of any kind and sticking RS-232 ports on it in 2009 shows that HT component makers are totally out of touch, not to say morons. IMO, YMMV, you get the picture.
You don't need a diagram as to why this is so -- if they had WiFi, they could talk directly to your iPhone or laptop right now (given software). If they had Ethernet, you could connect them to your home network, which would easily feed via WiFi to your iPhone/laptop. With USB, at least you could plug it into any computer without having to buy some hardware adapter. But RS-232? All that is good for is connecting to other, equally retarded HT components.