The lesson that the GOP-e has not learned is that there is so little “middle ground” and “independents” left in the political market place, that it is not worth pissing off the base to gain a point or two. When the base is not enthusiastic, and when they don’t turn out to support RINO candidates, the cost as a percentage of the vote is far to high.
In short, a moderate GOP candidate does not gain enough independent voters to offset the loss both motivation, donations and votes from the base.
Put it another way that goes something like this, social or Christian Conservatives may not be able to get a candidate elected all by themselves but a Republican candidate cannot get elected without their committed support. The record speaks for itself.