Yes, the medical professions are in the pockets of the pharmaceutical companies.
I think a good part of the confusion over the issue is that nobody knows, but many people have theories. You can't just skim a study, you have to read it in depth, and you have to know who paid for it. Many theories are supported by testimonials rather than real science. Furthermore, there are practitioners out there who have found themselves a niche making money from people, like us, who have a treatable, but incurable, disease.
When thyroid issues don't resolve, the party line is that the thyroid was already too damaged.
I've yet to hear of anyone "cured" (and the proponents of these theories seldom even claim to have a cure) or even substantially improved by diet. The exception, of course, is the junk food junkie who does feel better on a healthy diet.