I get what you're saying, but I don't think the problem is nearly as bad in the Democratic Party as the Republican, and I'm not sure what one can do stop some people from getting pissed off and ranting about it, especially on message boards. Telling them to shut up certainly won't work, driving them out of the party for complaining is a bad idea, and message boards are always going to have people complaining about something, and "purity tests" have been around in American politics since the Salem Witch Trials. I don't like them either, all I'm saying that it's a part of human nature and that I'm not sure there's any real way to stop it in either party. And right-wing media is always going to amplify anything any Democrat says to drive a further wedge between the GOP base and Democrats.