What it seems to me that you’re suggesting is essentially crowd sourcing a mix of investigative journalism and data analysis, which is not a skill I think that just anybody can pick up and do properly. To be fair I’ve never tried my hand at investigative journalism, but I have done a few units of data analysis and trust me there’s a hundred different ways to do it wrong. Even among the experts, there’s a lot of disagreements to what the best approaches are. I had a teacher even say that if you give a set of data to 10 data analysts, you’ll get back 12 different ways of interpreting it.
That is all to say that I’m not sure how much you’d be solving by providing another forum for people to post their takes on public policy issues, but then again if you manage to attract the right crowd of critical thinkers, who also happen to be open minded enough not to insert their own agendas into matters, perhaps people might hold each other accountable?
BTW have you checked that something similar doesn’t already exist? Insert obligatory xkcd comic:
I wish I could just up and buy a farm, that sounds like the life to me.