This is a math thing:
The U.S. Remained Center-Right, Ideologically, in 2019
There are more conservatives than progressives, and a ton of moderates and center-right people. The country is too uneducated and selfish, even though they ideally might like certain ideas.
Progressives are a minority in America. To win, they need to compromise | Michael Lind :
"Not only are progressives a minority of American voters, they are also a minority of Democratic voters. According to Pew, in 2020 only 47% of Democrats described themselves as “liberal” or “very liberal”. The majority of Democrats are “moderate” (45%) or “conservative” (14%)."
It is no surprise we have a significant amount of Democratic moderates who are fine throwing all these policies away. They care more about getting elected than they do systemic change. They dgaf.
Of course, it's not all of Dem senators. But it's clearly enough.