Because that person, that player, would be the one in charge, with power to manipulate the RP of the respective faction, regardless of what others thought, so long as he kept his clique of friends happy.
With any attempt to gather support around an idea, control ultimately resides in the audience, not the presenter. If we reject the idea being projected, they lose relevance and fade from public attention.
So I'll shake the olive branch one more time and try to turn this conversation towards what does and doesn't seem like going too far? What kinds of outlooks and positions on social issues make sense for which parties to you?
One the trust front, as well...what kinds of claims seem like they'd be out of bounds?
I can agree if I saw things like vote counts on made up Bills touching on controversial issues that have no citations I'd cringe a bit. However, as long as it stays broadly general, I don't see much harm in it. As a student of literature/drama, I see these characters are simply icons, props, a vehicle for RP and a foil for other players' primary characters. This also reinforces their lack of staying power if they wander to far from the overall community comfort zone, since they are somewhat facades (no offense to the puppeteer :9).