Herbalists were different from ironsmiths and tailors in the sense that most of the ingredients ironsmiths and tailors required were from wild beasts, while the higher grade weapons would need all sorts of metals dug out from mines. They could hire people to do this sort of thing. In fact, they could just buy pelts and metals from the market. Once they processed them, they could cover the cost they spent to buy them.
Herbalists were different. They could only enter dense forests to collect their ingredients themselves. Usually, they would need to spend a lot of time and energy to search for just a few herbs.
And when they collected herbs, they also had to be very careful and professional. Not all people could collect the herbs as they pleased. If their skills were not outstanding, they could not ensure that the gathered herb was still in perfect condition, and the medicine they refined would suffer terribly in quality!
