Maybe I'm giving the original designers too much credit, but I don't think they're as dumb as the double-PtV theory you put forth makes them out to be. IMO, it's pretty clear that since YSANC doesn't discard any defense, it doesn't really have anything at all to do with ATE. In fact, it doesn't have anything to do with helping Vader deal damage at all. But it DOES function as a way to prolong the Duel, thus supporting the attrition PtV. Most movement cards are specials, and there are also a fair number of DD specials, both of which are eliminated by YSANC. So in this way it can both prevent the opponent from getting to Vader at will and reduce potential damage when he does. As far as assuming ATE is intended as a card to win the game, I really don't think it is. For one thing, I don't think anyone, the designers included, assume that building a deck with good support of "Play this card to win" is going to be fun to play. I mean, imagine if ATE was well-supported as a PtV. Would that be fun for anyone? This is why, yes, I am most certainly arguing there are not two paths to victory -- ATE isn't a PtV, and in fact, it can't be supported as a PtV or it becomes "Play this card to win." So although ATE "could win the game for Vader," the fact that everyone knows this means it isn't likely or expected to do so. But by the very same token, if the opponent ignores the presence of ATE and closes with insufficient defense... there are consequences.

In Italy for thirty years under the Borgias they had warfare, terror, murder, bloodshed, but they produced Michelangelo, Leonardo da Vinci, and the Renaissance. In Switzerland they had brotherly love, they had five hundred years of democracy and peace. And what did that produce? The cuckoo-clock.
- Orson Welles