Earlier quoted context omitted.
This is not true from a language/ word usage point of view. E.g https://www.amazon.co.uk/dandelion-tea/s?ie=UTF8&page=1&rh=i...
Well yes the term tea is used "in the wrong way" a lot and one could argue that it is common enough that it's the right usage these days (language evolves etc.). But technically tea is only from camelia sinensis varieties. So the "herbal teas" should technically be called something else like tisane.
Heck, why not argue that any “tisane” not made from barley isn’t a real tisane.