Boo fucking hoo. If you want to push leftist policies go ahead and make the case. Don't keep crying victimhood because folks who are not part of that prayer circle think it's bullshit.
That's not really how it works, is it? Power struggles within a party are never really about people "making the case" to each other in a dispassionate forum around a nice meal: see, the Tea Party. It's about gaining recognition, securing positions on influential committees, and displaying strength.
The progressives think arguing to the issues and principles ought to define the Democrats. They get a lot of airtime - a lot more than a bunch of established players, through social networks - and traditional networks, too. It's also how they got their strength, and they are attempting to show the party leadership that strength. They are, in a way, "making their case". Unsurprisingly, that leadership (who got into that position of leadership following an entirely different route) oppose those methods, and tend to dismiss that strength.
I am sure Pelosi is a great political player, but I think she is meeting very poorly the progressive's challenge - at least from the outside. At the heart of it all, is whether or not the rules and practices which have allowed both the current leadership of the Democratic party to rise to that position, and some candidates to hold on precariously to their seats, are adapted to current political conditions and climate, or sufficient to deliver victory. My own view, somewhat independently from my wish to see a more progressive platform triumph, is that prudence might be barely enough to secure a victory in 2020, but will not address the much deeper problem associated with the rise of Trumpism.