Moreover, because neither party can win enough seats to control Congress running only true believers, the prostitutes are essential to get control and give power to the ideologues. Therefore, the purists must tolerate the political prostitutes and work with them, no matter how annoying it may be.
At one time, almost all those who just want to win and don't stand for anything were Democrats. As a Republican, you would have been condemned to the minority, where you would have no power, get no media attention and have no fun. The place to be for the politically ambitious was clearly in the Democratic Party.
These people helped the Democrats in various ways. They provided the marginal votes to keep control of Congress, presented a more attractive public face for the party than the dour ideologues and helped shape and craft its program and message in ways that voters responded positively toward for decades.
The downfall of the Democratic Party in Congress really began in 1974. That year it won a huge victory in the wake of Watergate. Democrats had a margin of 2-to-1 in both the House and Senate. With such a large majority, the ideologues mounted a purge of conservatives from committee chairmanships and other leadership positions. They thought their control was so secure that they weren't needed.
This began a huge shift of Southern Democrats into the Republican Party at the congressional and state legislature levels. By 1994, this transition was complete and virtually every political conservative had left the Democratic Party for good, giving Republicans control in both the House and Senate.
At this point, the prostitutes switched parties as well. The Republican Party became the place where the action is. It was the place to go for those motivated only by ambition. This helped the Republicans for all the reasons that such people had previously been assets to the Democrats.
The prostitutes' switch from the Democratic Party deprived it of potential winners and effective strategists. The party was left only with those who view any deviation from the party line as heresy. Such people don't know how to win and don't really want to. They would rather die for principle than settle for half a loaf. That's the Democrats' problem today.