This is just wrong. When Biden inevitably loses this election, this debate will forever be discussed as the turning point and every decision the inner circle of the party made in the 18 months leading up to it and after will be debated. The debate convinced the vast majority of Biden voters that Biden is flat out unfit to be President for another term. Full Stop. The result will be a bunch of those in the category of "reluctant" Biden Voters or pure Anti-Trump voters to sit it out or vote 3rd party. Because the reality is neither of these candidates have any business being President. The competent American public recognizes what a ridiculous choice it is and the reality is many will just throw their hands in the air and say fuck it, wake me up in 4 years.
The margins were slim to begin with but relying on the non R voting public to actually make an effort to vote on the basis that an essentially incapacitated Biden is still better than Trump is not a winning strategy.