If we can't account for where the money is coming from, how much assurance do we have that other countries are not influencing our election results, through their money. Plus, do multi-national companies, who also contributed anonymously, have our interests in mind, or just their own.
The size of a nation’s capital markets is directly proportional to the size of its economy. The United States, the world’s largest economy, has the biggest and deepest capital markets. Capital markets are increasingly interconnected in a globalized economy, which means that ripples in one corner can cause major waves elsewhere. The drawback of this interconnection is best illustrated by the global credit crisis of 2007-09, which was triggered by the collapse in U.S. mortgage-backed securities. The effects of this meltdown were globally transmitted by capital markets since banks and institutions in Europe and Asia held trillions of dollars of these securities.
I have a flash light. 
...it's all the same. What we're talking about here isn't dark money, but to what degree are we going to legalize bribery.
Politicians raising money from various groups or people is nothing more than bribery. Widespread, blatant bribery.
That's what lobbyists do for a living. They bribe Congressmen. That's what Political Action Committees do. They raise bribery funds.
That is why this country is fucked 6 ways from Sunday. No one can be a member of Congress or the Senate unless they agree to take bribes.
than that of the current American political system.
Just their own