From The Atlantic, How American Politics Went Insane by Jonathan Rauch

Parties, machines, and hacks may not have been pretty, but at their best they did their job so well that the country forgot why it needed them. Politics seemed almost to organize itself, but only because the middlemen recruited and nurtured political talent, vetted candidates for competence and loyalty, gathered and dispensed money, built bases of donors and supporters, forged coalitions, bought off antagonists, mediated disputes, brokered compromises, and greased the skids to turn those compromises into law. Though sometimes arrogant, middlemen were not generally elitist. They excelled at organizing and representing unsophisticated voters, as Tammany Hall famously did for the working-class Irish of New York, to the horror of many Progressives who viewed the Irish working class as unfit to govern or even to vote.

The old machines were inclusive only by the standards of their day, of course. They were bad on race—but then, so were Progressives such as Woodrow Wilson. The more intrinsic hazard with middlemen and machines is the ever-present potential for corruption, which is a real problem. On the other hand, overreacting to the threat of corruption by stamping out influence-peddling (as distinct from bribery and extortion) is just as harmful. Political contributions, for example, look unseemly, but they play a vital role as political bonding agents. When a party raised a soft-money donation from a millionaire and used it to support a candidate’s campaign (a common practice until the 2002 McCain-Feingold law banned it in federal elections), the exchange of favors tied a knot of mutual accountability that linked candidate, party, and donor together and forced each to think about the interests of the others. Such transactions may not have comported with the Platonic ideal of democracy, but in the real world they did much to stabilize the system and discourage selfish behavior.

Middlemen have a characteristic that is essential in politics: They stick around. Because careerists and hacks make their living off the system, they have a stake in assembling durable coalitions, in retaining power over time, and in keeping the government in functioning order. Slash-and-burn protests and quixotic ideological crusades are luxuries they can’t afford. Insurgents and renegades have a role, which is to jolt the system with new energy and ideas; but professionals also have a role, which is to safely absorb the energy that insurgents unleash. Think of them as analogous to antibodies and white blood cells, establishing and patrolling the barriers between the body politic and would-be hijackers on the outside. As with biology, so with politics: When the immune system works, it is largely invisible. Only when it breaks down do we become aware of its importance.