I understand that feeling in regards to the Master Gardener designation- I went through the training and volunteered as an MG in NJ (US), and I have felt that way myself. I honestly think the name is mostly the problem. Taking a brief training course and then being called a “Master” of something is a bit over-the-top, and all of the dedicated MGs I know feel that way. During the training, it was always emphasized that our goal was not to ‘know everything’, it was to know where and how to find good information on plants/gardening (starting with our land-grant university) and help the public find the information they need- more like a librarian than a doctor.
The Master Gardener program itself is wonderful, in my opinion, as it fills two needs- 1. Volunteering as an MG is a great way to learn a lot about gardening and connect with knowledgeable mentors. 2. The MGs offer the public free gardening advice, which has helped many people deepen their connection with plants/nature/the environment. I just wish they were called Mentor Gardeners or Garden Buddies or something less grandiose.