It confuses me that someone who clearly isn't generally forming stances based on low-information, would put any stock in such a low-effort, poorly-fitting comparison.

I am flattered and a bit embarrassed that you got to peek at my post history on a bad day! Thank you. That said. I do not feel like it is a poorly fitting comparison. The Tea Party movement can be seen as a party revolt from the extreme right against what they felt, rightly or wrongly, for more moderate and compromising elements of their own party. This caused something of a rift within right-wing identity between conservative on the tea party side and the party leadership who they felt were betraying their core interests and ideology.

I feel like this is extremely relevant to what we are seeing within the left right now.

Tell me, what have been the costs associated with "this new democratic equivalent's demands for ideological purity", so far? Seems to me like the only "cost" has been to start incrementally dragging the Overton window to the left.

No costs, yet, but from my previous point one can very easily see costs arising.

Honestly, you mostly sound like you are sour, about the fact that millennials being a bit more idealistic than cynical about the political system this cycle is gonna cost Hillary the nomination.

I am a millennial, myself, and I don't really appreciate the assumptions. I have three requirements for supporting any particular candidate. 1.) They must have some foreign policy chops. 2.) They must have a foreign policy history that places greater importance on East Asia than the Middle East. 3.) They must not be militarily isolationist.

Of all the candidates, Hillary Clinton is the one who most fulfills my requirements. If it were Rubio, I would vote for him. If it were Bernie, I would vote for him.