Every Democratic campaign I've been old enough to understand could always be summed up with one sentence: "Vote for us or else the Republican will do evil things". A completely negative message, nothing about why I SHOULD vote for them, just about why I should vote against the Republican.
There's one exception. Obama 2008. This campaign was all about all the good things he was going to do, all the positive change that was going to happen. The word "Change" was so associated with his campaign, it was a meme for years. And Obama won by an absolute landslide.
Now, of course, Obama's actual presidency, he didn't do ANY of that, and instead, was just another war criminal, like every other president. But I do believe a big reason why libs deify him so much is his 2008 campaign, and I think that carried him to victory in 2012 as well. (Even though in 2012, they DID do a bit of that "vote for the Democrat or the Republican will do bad things, and if I was able to see that after they did that with Trump, but applied to fucking Mitt Romney, I would've laughed my ass off).
Now, after Obama was so successful with "change", and the good stuff? We had the complete opposite. Nothing will fundamentally change.
Democrats really hate learning, not just from their mistakes, but from the stuff they did correctly.
There Is No Alternative