It was a suggestion made back when the PB was released. It makes it easier to troubleshoot questions if you know what a person is running. For instance dual G4s have a problem with the modem script. Its easier to help someone with a modem problem if you know that they are running a dual G4. Its not required but it does help us help you.
iMac DV SE, 400mhz G3, 256 MB
MS optical wheel mouse
Wacom Intuos A5 USB (doesn't work with X or even Classic)
USB Zip 100
Freecom Traveller USB (doesn't work with X)
Epson 640U USB scanner (doesn't work with X)
HP deskjet 970cxi USB (works with X!)
Networked with a Windows 2000 Pro PC (using it for Internet access), a SuSE 7.0 Linux PC and occasionally a Windows ME notebook, all over 100mbit ethernet.
PAL Sony PC1-E DV camera over firewire (works fine with iMove 2)
SCM USB Smartmedia adaptor (does work with X)