DVDs are available but: 1. thousands of users don't have them/can't afford them 2. many can't boot from them even if they did have them
My installations don't use optical media. Instead, I use the Anaconda option to mount the ISO images I have on the HD. I just need one CD to boot from, and it doesn't need packages, just enough stuff to find the HD and mount the ISO images.
I do this mainly for upgrades, but it also works when adding Fedora to a Windows system, and I expect that's the more common use case.
