Well, they could be biased...but then again, they have no miracle claims for vitamin C there. And I did say they were a good starting point, and they have reference cites to support health claims. So you can read the references to see if the evidence, IYO, is strong enough to support the claims.
They do it because there is a profit involved. If a cheap, not patentable supplement works to correct or prevent a health disorder, then a costly drug is not needed/prescribed. That cuts into potential profits. If the benefit of a supplement becomes widely known and, therefore, more generally used, that will cut into profits significantly.

OTOH, companies can make a profit on the other side as well, they can put in a little, ineffective or inert form/amount of a proven effective supplement, make health claims for their "improved" product and sell their product at either a premium price or make it more marketable.

True. That's where self education and knowledge come in. Bogus science is bogus science, no matter who is paying for it. The same can be said of good science as well, though. That's why media reports need to be ignored and original studies, on which the media reports are based, need to be read and the "evidence/facts" analyzed to find the truth.