This so-called "thought" provoking article fails to address the reality that (1) members of the ideological "base" of each party are more likely to vote; and (2) people in the middle are focused more on candidates, rather than issues, and can be persuaded to vote for a more ideologically pure candidate who articulates well-reasoned policy positions. It is more difficult to alienate a group that doesn't know enough about the issues to form a coherent ideology, than it is to alienate your base.
If your ideologically pure candidate is a bore - the other party's more appealing candidate will win. And if your ideological positions are out of step with the electorate - it will be a landslide for the other side.