It's still a party dominated by capitalists in a state that can never be reformed into socialism, ever. This is the basic problem, even if the Democrats were hardcore Marxists they still couldn't implement socialism even if they wanted to. That requires completely replacing the state, which is beyond the ability of those that take office, and requires armed struggle to take the commanding heights of the economy outside the scope of the state.
I'm very optimistic for the future, I just know that the Democrats are not on my side.