What is actually a meme is this need to squash the entire universe of unrelated political beliefs into a single axis of "left vs right".

The Democratic party is just as, if not more socially progressive than many European "left wing" parties on certain issues, that's true, but that's not what anyone is talking about. Issues like abortion and LGBT rights concern personal freedom, they're orthogonal to the left-right axis.

When we say that the Democratic party is to the right of every European left-wing party, and to the right of most right-wing parties, what we're talking about are the economic policies that affect the lives of everyday people.

US democrats can't even get behind table stakes leftist issues like universal healthcare, social safety, progressive taxation, and wealth inequality. They know who pays for their re-election campaigns and who controls the media - it's not the working class. Democrats aren't leftist, they're liberal, which is a night and day difference.