We said that in the 2012 primaries. We said something similar in 2008. We couldn’t say it in 2004 because it’s not cricket to primary an incumbent President.
We tried it your way twice and there are already those who want to try it your way again in 2016. Those people are GOP-E.
At what point do we realize that a national party incapable of winning national elections due to its selection of centrist and center-left candidates deserves the fate that’s coming to it?
You're right. Let's instead keep supporting a Republican National Committee that opposes conservatism and cannot win a national election.
There are two reasons to start a third party:
1) To bring the Republican Party to the realization that it will lose its power and its influence, which are the real reasons it exists, if it continues to ignore its base. If that leads to discussions about how to genuinely improve the Republican Party, great.
2) To supplant the Republican Party as the home of conservatives and conservative Democrats (i.e., the Reagan Coalition). If goal one is not reached, the Republican Party deserves to go the way of the Whigs.
Or, we could do it your way, keep nominating losers like John McCain and Mitt Romney, and keep losing national elections. Up to you.