I guess it comes down to "let they buyer beware."

There are alternative therapies that work.
There are some that are scams, and effective only in divesting you of money.
There are some that will harm or even kill you.

If you're interested in a particular type of therapy, get as much information on it as you can. First find out if it can be harmful, then find out if it's likely to work. I looked at Wolfgang's site, at the paper they had on kava-kava. They didn't say it was ineffective - quite the contrary - but they did list potential problems with it. What they said about herbal preparations has also been true in my own experience: there is no regulation, no quality control other than what the manufacturer applies, and potency varies from brand to brand.

It makes good sense to be as skeptical of alternative therapies as you would be of allopathic ones, and don't rely only on "I heard X was good for your condition," or "X worked for me."