The story of the rise of Chris Van Hollen is very telling.
Van Hollen started his career being very skeptical of the very reliable US support of Israel and the congressional sense that Israel can't do anything wrong. That didn't last long, he was quickly pulled back into the fold of strongly pro Zionist politicians, which is nearly all of them (including especially Hillary Clinton).
Some of what is described, such as being organized, visiting a congressman, and threatening not to vote for him, are just exactly the ways the political process should work and illustrations of what everybody should do to advance their political priorities.
But the part that involves campaign contributions, super PAC funded advertisements, and threats from mega donors are illustrations of how the US political system is corrupt--rotten to the core.
As Molly Ivins once wrote, anybody who is a real Democrat should support Single Payer Healthcare and Publically Financed Elections. Molly did not like triangulating politicians, and specifically mentioned Hillary in that regards.