Whenever I try to do a recipe that calls for support and I don't get it (even several ranks below me), I get serious fails, and frequent unstable elements. But I can succeed on recipes several ranks above me without support (if they don't call for it).
Exactly, I've had the same experience thus far while leveling about every craft besides cooking to ~20-25. People are assuming that it works similarly to FFXI where it added to your crafting level, but I don't believe that is the case.
Of course I don't have proof for this either, and it would likely be difficult to test.