Completely exasperated by your refusal to hear what people keep telling you
After all, I think we can agree that in Murica 2017 a "purity pony" is anyone who would properly be recognized as a "New Deal Democrat."
No. You want it to mean that. You insist that the insult is directed at anyone with specific policy positions.
People who use the insult - and yes, it is one - are talking about the political strategy of voting for candidates with a statistically-zero chance of winning. Doesn't matter what the actual policy positions are.
You conflate the two so that you can insist anyone who votes for the lesser evil obviously is no true