In this case I support Glass as an intermediate material that makes sense. Glass would be part of so many other professions; such as alchemy or engineering.
I think, though, that the raw material should be left as sand before processing; maybe mined by the mining profession? Or harvested directly by a glassblower.
Initial Material - End Product
Glass Sheets - Goggles, Windows, Lanterns
Glass Bottles - Potions
Although I cannot see much more use than that at the moment.
Thinking of it, though, every profession will start having intermediate steps anyways, even if we don’t really see them. Miners harvest ore that has to be smelted and then smithed. Farmers harvest plants that then have to be processed and cooked, perhaps even using wood that lumberjacks have to harvest. (coal?)
I think their basic premise is that it’s had to add something to the game. I think glass-blowers could do that.