The author makes a provocative statement that the initial vision of what governance in the US would be was transformed by that election. It gets to the heart of what a political party is. This quote picks up with a discussion of whether contributions pose a rick of "quid pro quo" corruption - a donation made with the expectation of a service performed. If I understand the argument - the author seem to suggest that the decision ignores the likelihood that such corruption can occur through an umbrella agency that impacts a significant number of members of Congress, rather than a single members.
The idea of a Congress composed of separate individuals acting independently ended a long time ago - with the 1800 election:
The argument is a simple one. If the base contribution limit defines the point at which a risk of quid pro quo corruption is present, adhering to that base limit should take care of the corruption risk, no matter how many base contributions are made, rendering the aggregate limits unnecessary. Watching the government twist in that airless room trying to build Rube Goldberg scenarios explaining how a $3.2 million aggregate contribution can seep down to individual candidates or entities in amounts that exceed the base limit would have been funny, if so much weren’t at stake. You knew that five Justices, dead set against the regulations, would reject the government’s scary stories as either unlikely, or subject to other forms of regulation. And that’s just what the McCutcheon plurality does, insisting that the real-world prospect of a single donor cutting a check for millions of dollars to an umbrella entity poses little or no risk that any of the money would find its way to constituent entities in ways that threaten quid pro quo corruption. After all, if you don’t believe that massive independent expenditures on behalf of a candidate pose a risk of electoral corruption, why would you be concerned that even unequal distribution of aggregate contributions poses a risk of quid pro quo corruption of any given recipient? Even on its own terms, the Roberts plurality simply ignores the fact that political decisions are not always, or even usually, the result of atomistic decisions by individual legislators. That was the initial vision of the Founders. All agree that the Founders’ vision did not survive the election of 1800, and that today’s politics take place in the shadow of collective decision-making by political parties, or other less formal political groupings. To the extent the Roberts plurality has a technical flaw, it is the failure to address the risk of quid pro quo corruption in the context of a deal with a group. But I’m afraid that train has left the station.