The real trick i think is 'Optimal Level' VS 'Required Level'.

with 'Optimal Level' gear, i can, and did start spirit-bonding 41+ gear from level 1.
with 'Required Level' gear ... you can't get high grade materia till you are the proper level.

In any case, i've made over 900 items from spirit-bond since the system was implemented.
If not for optimal level gear, i would be half that far at best.