That's all true. But her campaign is the tool that we had in that moment. We did it before with Biden. We could have done it again with Harris. In the months leading up to the election we've got to care less about the quality of our tool and more how we use it. We can push the Democrats all we want further to the left up until then.
But the campaign we get after the DNC convention is the campaign we have to use. Some people couldn't put aside their moral self-image to do that. Now they're beating a dead horse, when Trump has threatened to send those Democrats to prison. We could all be heading to death camps starting next year, and I'm hoping I can reach some people to get their heads in the game before that.
If any neoliberal can't get on board that neoliberalism is dead, then obviously they are no use to us. But they are an easier pool of people to convince than the fascists who want to kill us. And if the Democratic Party still exists in future elections and there somehow are future elections, both seem unlikely, it's still worth voting for them because it gives us time to get a populist campaign off the ground assuming there isn't already one that's ready to go. edit: typo