The parallel to naturopaths, chiropractors, acupuncturists is also a good one for a practical reason: it's very hard to find a "good" one in a sea of mediocre (or even BAD) ones. Speaking for myself, I'm not averse to a nutritionist, I'm averse to spending my time and money on people who don't meet my needs. 

 If you don't have a large word of mouth network, it's really hard to find "good" people - this does also extend to doctors, nurses, RDs, whatever, but I think there's a certain amount of assumption that a doctor (RD, RN, NP) has at least some baseline level of knowledge.
So, in the interest of sharing knowledge, how do we find a good nutritionist or dietitian in either case? I didn't think about the university sports medicine, that's a really good idea.