Are you saying the dems should've run Biden?... I think using that one specific circumstances is a bit arbitrary. I probably would've used the the 2016 Primaries with Bernie if I were to refute my point personally...
That said people are primaried out all the time. AOC herself won by primarying out an established dem.
Let's say AOC (for example can be anyone) attempted to Primary out Schumar. Either she wins and gets to further a social democrats agenda in NYS and start to pull out the roots of the corporate Dems. Or if she loses she has a platform to spread her message and inspire people on more local tickets to start to cut out the roots that way.
There's really no reason to be doomer about an attempt to primary out Schumar.
I mean she does sometimes so not going to fully disagree with you. However she is currently on tour with Bernie pissing off Chuck and Nancy lol
That said doesn't need to be her necessarily I just mean that fielding someone to challenge would be good.
We gotta do something though as a whole, and I don't see why executing every potential avenue isn't beneficial. Run a challenge, run as an independent etc