Congratulations, that makes you a member of the largest DNC voting demographic! But the DNC doesn't win elections based on internal pluralities; if it did, we'd be living in a very different political landscape.

(To be clear: in a sufficiently dire situation, I would also vote for a cross-party ticket. But I know a lot of people who wouldn't, and there's a basic sense that their lack of turnout matters much more than my tepid support.)

Sounds like they were going to get your vote either way so why would the democratic party go for this?

The issue is whether the Democrats would lose more votes than they gain by shifting rightward. PP was providing evidence that they would not.