Started by DeBeers
Of course, this is all based on the work DeBeers did to lock "Conflict diamonds" off the market. The concept was/is the same -- the assumption is these conflict diamonds come from mines where the money goes right to warlords and such. The reality is, DeBeers really didn't care where the money was going, they cared where it wasn't going -- these diamonds were being sold outside of DeBeers distribution system, and DeBeers big fear is that a large outside source of diamonds affects the supply and therefore lowers prices.
So, really, the affect of this was not thought through to begin with, since the true goal was not to help the people in these countries in any way. I think those pushing for "conflict minerals" legislation just assumed the conflict diamonds thing was so successful, so let's do it for minerals (without looking at what the effect of the conflict diamonds legislation was either.)