Actually, what Sorel is talking about is how I thought of this once.

I doubt it will happen (like most of you) but a "weaver" is not a sail maker, though the skills are similar.
You could specialize in group activities (like making a ship) and such.

Considering Jobs & Abilities will be quested, it would not be all that unreasonable that if a Weaver wants to make sails (better/faster/stronger) they could take a Job Quest to specialize and quest for some sail making specific abilities.

I think it's a stretch, because "Job" system is supposed to bring back some Final Fantasy flare (like White Mage, Thief & Monk) and there was no such "traditional Job" for "weaver" in the past. Still, it could be done and done well and fun for Crafters to collect more skills and specializations for "group crafting."