Those that seek to persuade others (salesmen) get locked into their point of view. This isn't just because they have a whole pile of products to sell, which have a cost that needs to be recovered, but because we would prefer that our psychological commitment to a point of view were not for nought. The Id (ego) wants us to be right.
In politics ideas are peddled with great effort and politicians seldom want to be perceived as being wrong. There is a political cost to their ideas, measured in terms of credibility. This means that controversial points of view may not be raised as the associated risks to credibility and ego are too great.
Interactive Democracy allows the general public to push controversial ideas forward. They have little to lose in terms of political credibility. Politicians can at first watch the debate from the sidelines without committing to one side or the other, only later becoming involved in Parliamentary debate. This dynamic, very different from today's political system, may lead to more creativity and diversity in the range of public policies from which we may choose.