Answer:
Some people claim herbs are safer than pharmaceuticals because they are natural, but this isn't strictly true - plenty of plants are deadly poisonous or have side effects if used improperly. Many herbs have a long history of use, however, so it's clear what effects they have and the danger can be avoided, whereas the long-term effects of new medicines are unknown.
Sometimes herbs are less effective than prescribed medication, but other times they are more effective and it makes good sense to use them. Also, if you are geographically isolated and can't get medical treatment you can use local herbs instead, though this takes knowledge and experience.
Perhaps the biggest advantage is that herbs are cheap and you can get them without a prescription, so it's easy to treat yourself. Many people prefer not to depend on a doctor for their medical needs. Going to the doctor is inconvenient, expensive, and potentially dangerous if you are mis-diagnosed. Many doctors are stressed and over-worked, and there's a real chance they'll do more harm than good. Furthermore, illness can be a very personal matter and people are often reluctant to share the details with a stranger. This isn't to say everyone should treat themselves, but those with the intelligence and wherewithal to do it properly might be better off not relying on a doctor.