Why do people think Bernie would have done worse than Biden?

[Pericles]

It seems obvious that Bernie would have done worse. Biden did fine with turnout since he got 81 million votes, there aren't a lot of voters who would have turned out for a different nominee. So if Bernie wasn't needed to energise the base, it's hard to see the upside for him. Sure, he might have done better with Latinos-but those who swung to Trump had conservative attitudes anyway and whether they voted for him because of attitudes on the economy, policing or Covid, it's hard to see how Bernie would have been more appealing. Biden did well with white voters, who are more numerous than the demographics that swung to Trump.

Bernie wouldn't have had much appeal to moderate voters, he would have been much more tied to the unpopular stances Trump tried to attack Biden on and stuff like the 'socialism' issue and MedicareforAll would have hurt him. Biden won because unlike Clinton (this is odd but true) he was seen as more moderate than Trump. And in-person canvassing doesn't matter that much, those things are only worth a few tenths of a percentage point and are nothing compared to the image and message of the candidates. So Bernie wouldn't have gotten many more voters and would have been less appealing to the swing voter Biden flipped-so Trump would have won the Electoral College.