Feinstein doesn't tow the far-left line. That's perfectly reasonable even if they sometimes came be poor decisions that can merit fair criticism such as her Iraq War vote.
When her California colleague is one of the most liberal senators in the country and gets attacked by the left for being too centrist you realize they have a structurally problem. They don't gasp that politics is serious business, that you aren't going to get your way just as a child will be denied at points to not do something because his parents said so. Why does one negative contradict all of the good someone like Feinstein has done for Cali and America?
So since politics is a serious business, senators shouldn't be held accountable for basically being useless when considered she's in an uber safe seat? You win some races and you lose some but that's not a good reason for activists to not try to get the most left wing senate possible. Give valid reasons for a Democrat like myself to vote./support for Feinstein over KDL to back up your claim that she's done a lot of good. Voting somewhat left wing in a polarizing right wing congress does not count.