If alternative to medicine (ATM) was only about coping with minor inconveniences of life, it wouldn't be a big problem. But ATM is also advocated as a replacement of conventional treatment of very serious conditions such as cancer, diabetes etc.
Here is an analogy, that might help you see the problem:
Suppose someone was able to convince people, that it is the liver that is responsible for the circulation of blood, and not the heart. The solution to circulatory problems is not heart medicine bur abstinence from alcohol. Big Pharma manufactures heart medicine, so they are suppressing this revolutionary knowledge.
If someone asks this question on Y!A: "Is true that abstinence from alcohol cures circulatory conditions?" I think it is fair to point out, that it is nonsense, and that the prescribed conventional medication really is the best option. And if another answerer - we could call him "The ear understands" - answers yes because Big Pharma wants profit instead of cure as explained on Dr. Raviolas website, it is fair to point out the flaws in his reasoning.
in spite of the implausibilities, many of the alternative therapies have been studied under controlled conditions to see if they work anyway. I think it is fair to reference those studies when answering these questions. Sometimes there really is evidence of absence and not just absence evidence.
About the second part of your question, I think our answers are being helpful. It is not just the asker who reads the answers. I found Y!A, when I was researching on a particular type of cancer quackery. I am absolutely certain, that some people looking for treatments of various serious conditions will find these questions/answers too. By giving these people the information we have, we are giving them a chance choose on an informed basis.
EDIT TO ADD:
The remark from one of the answerers:"...we don't care about the evidence. we are happy with what we see." is really remarkable, and illustrates very well why our inputs are needed in boards such as this one.