So you are basically arguing to continue the Biden campaign, unless he steps aside and anoints Harris?

It all depends on how bad he is. And we don't know how bad he is. I rank the options as follows:

Best option - Sharp Biden continues
Second best - Slow Biden yields to Harris
Third Best - Slow Biden continues on
Bad choice - Slow Biden yields to wide open convention
Worst choice - Completely shot Biden continues and drags every Democrat down with him

If he's actually in really good shape, and the debate was really just a completely-out-of-nowhere "worst cold on earth" one-off anomaly, then the Biden campaign is easily fixable and he's vastly better than any replacement Democrat. In that scenario, "Keep Going, Joe!"

If he's in mediocre shape, then maybe the Democrats are better off keeping him if the alternative is to go to an open convention. Because while a Harris candidacy has an underdog chance of winning the Presidency, and probably a better shot than a "slow" Biden, an open convention has only a moonshot chance of winning the convention.

But if he's in really bad shape, then even the convention is better than him sh!tting the bed at the September debate and avoiding any campaign event where he's not reading from a teleprompter. Because that tanks all the frontline House candidates in purple districts who are needed in order to keep a Trump-led GOP from trifecta control of the federal government.