I will tell you how Manchin and Sinema can push their agendas and progressives can't. That is because the majority of Dems will side with Manchin and Sinema. If establishment Dems wanted to stop Manchin and Sinema they would constantly bring up the fact that they are getting in the way of things getting done. They don't do that though. Instead they get behind the same bipartisan bullshit that those 2 are pushing. Now if a Progressive tries to do what Manchin and Sinema are doing the establishment dems aka almost the entire DNC will smear them and say "Do you see? We can't pass this infrastructure bill because of Sanders. We couldn't help anyone during the pandemic because AOC was pushing for too much, etc." And then they will get bounced out of office. Nothing will get done. And you will no longer have leftist voices in government.
Your sheep dog claim is next level stupid. What fucking sense does it make for someone like Sanders to be this deep cover foil to the leftist movement when he himself has made leftist policy more popular than ever in this country? That seems self defeating if the goal is to stop progressives from gaining influence. Jimmy Dore wouldn't know what the fuck M4A is if it weren't for someone like Sanders. And it is really odd that he spends more of his time attacking progressives and Dems more than he does attacking the Right who actively seek to undo what little social safety net we have. You claim Sanders has sat and done nothing with his position but he has. He brought the sister bill to the infrastructure bill. His version is basically the green new deal.
You have been on this board long enough. Look around, look who it is that is giving your dumb ass posts likes. They are all righties. None of them support any of the policies you or Dore claim to advocate for. None of them want M4A, student debt forgiveness, affordable college, anything that could address wealth inequality, etc. So if they don't want any of the things you allegedly want, and actually oppose those things. Then why would they be here agreeing with you?
It's sad that I had to spell things out for you like that. But you are really fucking stupid.