I was a Warren advocate in the primary. Sanders would have been an acceptable second choice; so would Biden. (Contrary to what the leftiest of leftists would claim, there's not a huge difference among any of the Democratic candidates--even Bloomberg--compared to where they stand compared to ANY of the Republican hopefuls in the 2016 primary.)

I'll agree with your point--that a Biden victory in the general election doesn't prove that Sanders might not have won had he been the 2020 nominee.

But will you agree with the inverse of your question: A Biden LOSS in the general election does not mean that Sanders would have won had he been the nominee?

I ask that because for almost 4 freaking years, I've had to listen to the magical thinking that if Sanders (not Clinton) had been the Democratic nominee, he would have defeated Trump.

Now I can't prove that Sanders would have lost to Trump, but it's equally impossible to prove he would have won. You can't PROVE that Deez Nuts would not have won (had he been on the ballot).

Are we so afraid of uncertainty that we will cling to any will-o-the-wisp possibility that we WANT to believe, rather than admit the limitations of our understanding?