Very interesting article with ties to Wall St as well as Siri. It should serve as a reminder that in business dealings, only -you- have your best interests in mind.
The provision of these products and services at all levels may or may not involve:
A) Either a vendor or customer of the business desiring or actively seeking to harm said business (i.e., the opposite of the businesses best interest)
B) Either a vendor or customer of the business having no opinion or and no interaction whatsoever with said business outside of the provision of product and/or services (i.e., having no interest in the business)
C) Either a vendor or customer of the business intending to help and/or provide worthwhile help to said business (i.e., having the businesses best interests in mind)
It is quite possible that a businesses vendors and/or customers do have said businesses best interests in mind (example C above). Examples A and B are also possible.
Saying that "only -you-" have your best interests in mind is certainly a possibility in some dealings, but my guess that other scenarios are also common.
I agree that it may be wise to assume negligence and double check extremely important matters to a much greater degree than normal. The scenarios outlined in the linked article are a perfect example of negligence, inexperience and lack of communication at many levels. But, at some time, you simply must trust others and can only use your wits, experience and the expertise of even more parties to ensure that those involved in your dealings are doing what they should to the highest professional standards.
The article says Dragon agreed to pay Goldman a flat fee of $5 million. What if Goldman did perform due diligence, reported the issues to Dragon, and caused the deal to get cancelled, would Goldman still get $5 million? I don't think so, but if their agreement says they should and I were in Goldman's shoes, I would find reasons to recommend against the deal, because, to earn $5 million, it seems much easier to just advise against the deal than to assist the transaction and bear the risk of a bad outcome. On the other hand, if Goldman gets nothing (or a fraction of the $5 million fee) in the event that the deal gets cancelled, it would be in Goldman's best interests to see the deal go through and avoid performing any potentially deal-breaking services (e.g. due diligence) not specified in the written agreement.
There are scenarios where vendors or customers do have the business's best interests in mind. One such scenario is when the vendor or customer has very close family relationship with the business owner (e.g. husband-wife, father-son, etc.) These scenarios are uncommon. To be on the safe side, I agree with the sentiment that only you have your own best interests in mind.