I think you're wrong. Lifestyle changes are usually not enough to change thyroid function, and there are some problems with continuing to have low thyroid levels. Low levels can degrade brain function, make people more at risk for contracting illnesses, make it difficult to lose or maintain weight and other things. These are things that ought to be avoided. Lots of people have low thyroid and think they can just "live with it," but that's not the case, and herbal medicines do not replace thyroid hormones. With all due respect, I have to say your advice would misguide people when what they really need is thyroid replacement and medical help.
Paired with thyroid replacement, I'm sure your plans would help promote overall health though.