Those are the people who do the nost work for the party. People who 'toe the line' are also those who tend not to do the work that gets people elected. People who care enough to think also knock of doors and the other work that gets someone elected. You won't find a thinking person you 100% agree with, but a mostly agree is better than a mostly disagree - and by doing that work you also get to talk to people and perhaps change minds.