Why not just write a law that limits all contribution to federal candidates be limited to $500 from citizen constituents? Wouldn't that also serve the same purpose?
Perhaps, but I could make a very strong argument that such a law would be a violation of the first amendment. And what of the "idle billionaire" like the Rat from Jersey who is perfectly willing to spend $80 million of his own money to buy a Senate seat? With a $500 individual limit, very few could compete with him.