I would urge you to remember that this post itself is a meme. Of course "a few leftists making memes" isn't the root cause, it's just one that I personally witnessed swaying people and that particularly pisses me off.
And yes, the Dems could've and should've done better, but I would like to be able to believe that people are smart enough to not commit suicide by apathy, and I feel justified in being pissed off at those who dragged the whole country down by failing to show a little self-preservation instinct.
Simple, because those are the people it should matter to. Those are the people with the most to lose. Those are the people who are more likely to have LGBTQ+ friends and family. The moderates don't give a shit and should never have been catered to in the first place, but these people tossed aside the people and things they claim to love in order to make a stand. That's why I expect more from them, because they're in a position to be more hurt by it.