I too would prefer Biden to step down, and go with a stronger candidate.
Having said that, i don't think anyone can win in a landslide in this day and age, the partisan divide and the electoral college, makes that impossible.
I think even with, say, Newsom vs Trump, even if has been convicted of crimes, you would see the same electoral map as 2020, plus North Carolina, thats about it.
Thats the extent to which "destroying" Trump is possible, now, thats obviously better than rolling the dice with Biden, just saying the electorate isn't all that flexible.