I wonder if it's a mistake to treat all "non-mainstream medicine" as a single group here.

I'm not a physician, but I find some elements of non-mainstream medicine (e.g. certain teas can ease certain symptoms) more plausible than others (e.g. burning down a mobile phone mast helps with prevent covid19 spread).

Absolutely, but it can be difficult for non-specialists to tell them apart.

The anti-5G nonsense is spread with a similar anti-government spin to the original post by Alex3917.

The herbal tea market includes everything from making your own ginger tea, to a box costing $20 and promoting some idea of ancient Indian spiritualism and vitality.

It is a mistake. One that is made by both proponents and opponents of non-mainstream medicine.

Here's a nice quote from the (admittedly strawman-laden, but imo still nice) Poem "Storm" by Tim Minchin (https://youtu.be/HhGuXCuDb1U):

Do you know what they call alternative medicine that's been proved to work? Medicine.

Of course the provedness of medical treatments can vary, but statements on a random online shop don't really cut it for me.