It's a fetishization of the aesthetics of liberal democracy as being equivalent to an actual democratic process. In other words, they believe that the system can't fail, but people can fail the system.
They hate us cause they ain't us, they are embarrassed that they don't have to gumption to not vote for spineless almost invertebrate liberals.
Real answer is they don't listen, when we tell them why they arent entitled to our votes and then complain we aren't helping team "left" when they move to the right and make more people clock out mentally and lose on broadly unpopular legislation.
They're religious fanatics, we're apostates who deny the omnibenevolence of their god, the American Civic Religion.
A certain section of Liberals have weak and frightened personalities that keep them from directing their anger at people on "their team" who have actual power. The thought that the Democratic party deserves it when it loses is too unmooring for them to handle, and leaves them feeling too vulnerable, so they have to protect themselves from that feeling by turning their anger on the people who supposedly betrayed the party.
Weak people have a hard time turning their anger against people they believe to be stronger than them; much easier to get angry at the relatively powerless.
Easier to scapegoat relatively powerless people in America (third party voters, Chinese, Russians, you name it) than to blame the slaveowner-designed system which makes it so that a few hundred thousand hogs in midwestern swing states decide presidential elections.
Liberals also need fascists to do the dirty work of capitalism, so they make sure not to offend fascists too much, and also compromise with them constantly (Florida 2000 for instance). Communists however are obviously not necessary to the capitalist imperialist settler-colonial project here in the USA however.
They do kinda make a frustrated sound when I remind them that we don't live in a swing state
Just this week, I saw some lib elsewhere who was still mad about Nader in 2000. Yeah, he was the real issue with that election.
If you had added Jill Stein's votes to Hillary's votes, Trump would have lost.
It was HER turn! Your selfishness did this! Refusing to vote blue no matter who! We have the right to take your votes for granted and give you nothing in return!
The same way these dipshits will claim to love democracy and how Bad Country is a one party dictatorship but then immidiately turn around and unironically suggest you voting for anyone other than the one party(which just happens to also be their party) is wrong and its your fault if things go bad. Which one is it? Can you vote for other candidates or not?
Obviously we know democracy is a stupid shitty concept to begin with but it is funny to see them play both sides always.
They are angry about not getting the win they feel entitled to but they can't get angry at the people who voted for the republicans because of the whole bipartisan compromise reaching across the aisle thing so they attack the left instead.
Liberals don't want to blame systems when they can blame people.