Here's why:
* Blacksmiths traditionally work with iron and steel, using a forge and hammer to shape metal.
* Celebrimbor worked with precious metals and jewels, crafting intricate and magical items.
* He was considered a "craftsman of the highest skill", specializing in jewelry and artistry, not the blacksmithing of weapons or tools.
Celebrimbor's work was closer to that of a goldsmith, jeweler, or even a metal sculptor. He combined skill with magic, creating objects of immense beauty and power.
So, while he was a remarkable craftsman, Celebrimbor was far more than a blacksmith.