No, qwerty, the website does not mention "useless" for port forwarding. It states, "Port forwarding can sometimes be difficult to configure, but provides a relatively safe way of running a server from behind a firewall. Since only a single port (or small series of ports) is exposed to the Internet, the computer is easier to secure. Additionally, port forwarding allows you to run multiple kinds of servers from different computers on your lan." (Homenethelp.com)
This mean that the single port or small number of ports is exposed to the internet but YOUR COMPUTER is secured which it mean your computer is safe and not being exposed to the internet. Also, you mentioned router design is no good, well, you are wrong also. The website states, "Many broadband routers have special port forwarding configuration screens for standard applications (FTP, WWW, Mail, etc) and special screens for custom applications." (PortForward.com) Their technology with port forwarding are specialized to configure the port numbers for any kind of applications.
Sometimes DMZ cause problems with port forwarding. Not all DMZ works with port forwarding. You need to turn DMZ off in order for port forwarding to work behind firewall in your router.
There are multiple applications such as MVP, OJO, VP200 and other to work together. If MVP and VP200 work with one port 1720, then it will conflict and won't work. That why it need new port numbers to get both working at the same time. If you used DMZ, for example, if you put in 192.168.0.26 which it is for MVP right? So, if you put that numbers in, it will redirect their calls to MVP instead of calling to VP200. Lot of people complaining about the calls being re-directed to MVP. That is why port forwarding is needed and DMZ need to be turned off so the calls won't be conflicting and won't be re-directed to any other VPs than your VP200. Why worry about DMZ anyway....your computer won't be affected anyway because your computer might be behind firewall so stop worrying about it.