As I said IANAL so I would not dream to cross swords with you on "duty of care" but IANAL has arisen because a lot of people on the web obviously do not wish to be thought to be giving legally qualified advice, especially as it may be taken out of the context in which it was given. This may all be a USA thing and not legally correct anyway so it may just be part of my paranoia but I wonder.
Re your second point, I am sorry if I did not make it clear (a common failing with me). I agree with you 100%, I believe people should state if they have an interest, regardless of whether they have "advertised" their occupation. If they had not advertised and were not trying to profit from the discussion, they would not have to go through the whole rigmarole of disclaimers which would only rile some others into trying to find out how they would profit from some friendly advice. SO I am still happier with voluntary privacy as long as people "play the game" and it would be unwise to enter any transaction without checking whether a person has an "angle" anyway. Sorry for any confusion.