App.net will use some basic algorithms to put in “presets” as a proxy for how useful that particular app may have been to you. The member will then be free to move the sliders in any configuration that they wish.
So if you don't fill out the form, they probably just use whatever their algorithm tells them you think. But since Defaults Are Powerful my bet is that the vast majority of people who do bother to fill out the form will either just submit the presets or a mildly tweaked version of same, so the survey is skewed towards their algorithm's findings anyway.
I bet they're going to love that. There's nothing people like more than filling out the same form over and over again, after all.