I know most of us are thinking that crafting support raises your level like in FFXI. If there is any proof of that please post sources. But for now I believe you don't need support unless it tells you to. I have seen no difference in crafts that don't require it with support on.
I see it as Common support such as using your dad's shop to make some stuff. You know, he would have a mid range of tools, benches and such to help you make your craft.
Guild support I can see as you heading into a workshop in the city that has some larger tools. some top of the line type equipment with some experts there to help you.
Masters support I see as you walking into a warehouse corporate facility where they specialize in what you are looking to make that pumps a unit every half second.
And without any of these your sitting outside with your own two tools, which do make for example bronze rings you don't need any other type of support.
My point is, If it doesn't say that I require any one of these facilities then why would I want to use it? What do you think?