If the voters, in large, supported progressive ideas as strongly as you do, Democrats would be passing more progressive laws. The issue is, you are outnumbered by people who don’t care as much as you. By people who have no interest in paying attention, much less participating. Those, like the person you were replying to, who are more willing to give up than to make change. The fight isn’t being upset that Democrats aren’t more progressive, many would be more progressive if it reflected what the voters want. The fight is energizing the voters about progressive ideas. And painting Democrats, who are immensely more progressive than conservatives, as the problem does nothing but destroy that energy.