Although becoming an adventurer brought pride and honor, becoming a craftsman brought immense wealth and status. In battles against monsters of all kinds, good gear could decide one's life and death.
No matter how arrogant nobles could be, they were wiser than to offend a craftsman. If the Craftsmen Union heard about one of their members being abused, they would forbid all craftsmen from working with the offender.
The main reason behind the creation of this union was the workers' exploitation almost five hundred years ago. Nobles and adventurers began kidnapping and harassing craftsmen to create gear for them nonstop without paying a dime.
The workers revolted, and the result was this union being created. In the present day, craftsmen could no longer be exploited because of the union. Once life changed for the craftsmen, they began growing stronger through the resources and wealth they obtained.