but web sites can be edited with about any program right? I mean to say, just because a sight was built with DW or FP, doesn't mean it can't be done with GoLive. One would simply need to download if via FTP into a working folder on the web design program, correct?
Yes and No.
Any site, regardless of what was used to make it, can be downloaded and edited with any program. You can even use any basic text editor like Notepad.
BUT FP, GoLive, DW, etc... use special codes for managing a sites templates, components, links, etc... Lets say i need to build a site containing 300 pages. I build a template that contains all the common elements, like logos, navigation, links, etc... Each site page is then made from that template. If i then change a common element in the template, programs like GoLive and DW, will make that change to every page of the site.
These template changes, and other site management features, are made possible by special codes in the original html files but not uploaded to the server. So if you download from a server you don't get all those special codes that make managing large sites easy.
In short, i'd say downloading small sites and editing them is fine, but for a large site you need the original files used to create the site.