Should Chinese Medicine and usage of herbs for health purposes be on topic?
Yes, in my opinion questions about everything that is meant to affect health should be on-topic.
As well as the questions about how the various things (like high heels etc.) affect health.
If you say, be on topic, do you mean like whether people are allowed to ask that? Why shouldn't they be allowed to? I say of course they can. It's the task of the answerers to either prove their answer (let's say that some particular herb has an actual effect or not) with some studies or point out that it's just their opinion or experience (like maybe when acupuncture helped in one's case).
My personal opinion is that snake oil should be called out for what it is, so as a general rule no.
But on that note if there is something which can be objectively proven (yes I mean double blind trials with a control.) then I think it should be on topic.