(b) "It makes appealing to the extremes less fashionable since they probably won't give you the support you need to win enough states."
This certainly isn't obvious. Please elaborate.
What I mean is that driving up turnout amongst the core base in places like Utah & Massachusetts isn't good enough. There are places like Iowa where swing voter turnout is high enough to make sure that people like Musgrave or Rangel wouldn't have a prayer at winning, regardless of how much they charge up the base.
Though those are extreme examples, the point remains that it makes it harder to win by just turning out your base since you'll be forced to compete in more moderate states.
At any rate, the argument sounded better when I first posted it than it does now.