Right where it says a presidential candidate needs to personally get a majority of electoral votes. That immediately means that a third party can only serve as a spoiler.
And yes, I'm not a fan of the Constitution either. Most other democracies either don't have one or (for better or worse) they rewrite it every few years. That way they don't have to contend with dumb questions like "what would James Madison think about assault rifles."
But if you're in this country and you think politics is worthwhile, this is what you're stuck with.