That's only a minority of loud leftists imo. Many of them are just contrarians who won't support anyone who can win in any party. Democracy cannot survive without compromise. Rightists and radical leftists will bring us all down if they continue to be philosophically uncompromising ideologues.
It's the entire DSA, The "Justice Dems", the entire Green Party, most of the Squad, most of the "Free Palestine" movement, and more. Yes, they're loud, but there are enough of them that they've thrown elections to Republicans at least three times in my lifetime (2000, 2016, 2024).
Well, if we fight among ourselves we'll never win again. We need to compromise with them when we can. New voters often have strong views but never actually vote in numbers large enough to have much effect. Acrimony within the Party certainly won't encourage them to actually vote!
Yeah, talk to them. They don't believe in compromise. Apparently.