I don't think this could be the motivation for running this statistic; afterall, in the same place you saw this, you'll probably also see reportage that the wealth in the US is becoming more concentrated.
If you're looking for a cynical explaination, I think you'd have to say that the implication being put forward with this statistic is that being in the market is "acceptable" if not downright American, so keep up the good work, troops!
/jordan