I've been mulling this one over for a few days and come to the conclusion that there's a number of different sets of qualities which might qualify an individual as being an 'expert' in gca.
There's the historical expert, who might have researched courses and architects of ye olden days and produced theses or books based upon that. There's greenkeeping/agronomy experts who will have years of experience in maintaining/improving the playing conditions at their course for the benefit of their members and perhaps even for the good of the planet in ecological terms. There's people who will have studied for academic qualifications in various related subjects who will have knowledge of the science or engineering or construction of golf courses. There's people in related professions who will have developed specialised knowledge in the subject for their work. Lawyers, accountants, property guys and so on.
I think one of the issues is that GCA isn't regarded in the same terms as the traditional professions. In order to call yourself an architect, a surgeon, a lawyer or an accountant, you have to reach an acceptable standard in your subject. Any eedjit can set themselves up as a golf course architect. Luckily, reputation and reference are still used as benchmarks, so we're not totally surrounded by poor design. Although, there's still enough around to suggest that the so-called experts, erm, aren't.
F.