I won't engage on most of what you address here, because there is so much backstory and it's all so complicated, I would need a book. Anyway, what do I know? This, however, is patently absurd.
Democrats and Republicans alike now believe that Joe Biden completely bombed the debate on purpose
First of all, I don't know any Democrats who believe this. More importantly, have you watched the man? He had to be dragged kicking and screaming from the race. Ego got the best of him. For some reason, he thought he, and only he could lead the battle successfully.
He is bitter, and will probably die a bitter man. You could write an ode to narcissism featuring Trump and Biden as anti-heroes. They are both consumed with their place in history, and their own superior mission.
Biden was kicked out, and he was kicked out none too soon. It's embarrassing to watch him now...not because he is old (I am old), but because he lacked the humility to step aside when time had taken its toll.