It looks to me like we need to avoid looking at officially-stated reasons. They so seldom line up with the stated problem, nor do they solve that problem well, or without side-effects. I'd say to keep an eye on the obvious side effects: they may, in fact, be the reason for the solution-that-doesn't-really-work. I also believe that classical market economics under-appreciates the desire of managers/directors/etc for control. A link tax would allow those in charge of corporations to control the information they report, and to control the people that want to use that information.