I think you have answered your question already by citing the OU article. See https://en.wikipedia.org/wiki/Vegetable. To me, this seems to define herbs within the vegetable family.
Since the OU article you cited says that vegetables "do not require checking", this would apply to dried herbs as well.
This OU page (Hmm.. OU has a lot of good food pages!) seems to classify herbs and vegetables alike. You'll see several items which are commonly considered "herbs" to have the bracha borei pri hadamah just as any other vegetables. For example, dried and candied ginger (ginger is commonly considered an herb) gets the bracha adamah. As for something like chives being shehakol, that's probably because it falls under a different rule stating that when you eat a vegetable in its raw state when it is commonly cooked, you would say sehakol. See the same issue regarding raw garlic.
I'm uncertain what they mean by "spices" as to why this gets Shehakol. I'd have to contact the OU for clarification on this as "spices" is a vague term.