Has it occurred to you that making that assumption could also result in suppressed voter enthusiasm? Put yourself in the head of a genuine lefty who’s fed up with Democratic shenanigans. What messaging might keep you in the fold, and what will drive you away?
Something else to keep in mind is that it’s not just voting that we’re talking about. Democrats need volunteers, donations, and word of mouth. Broad enthusiasm is critical for all of that. Who wants to volunteer for a movement that denies them a voice?
For decades now, every election has been called the most critical of our lives, and sadly it’s been pretty consistently true. We have elections every two years. Criticism in the first year is called unfair because they just took office. Criticism on the second year is always called disloyalty in a critical election year. Disinformation is only going to be getting worse, so waiting for that to end is not viable.