I don't really disagree with this but my opinion is that basically no one is capable of winning a US presidential campaign in the modern era in a matter of ~100 days. The fact Harris was a uniquely bad candidate that weirdly refused to differentiate herself from Biden, just exacerbated that problem.

If Biden and his administration had not been so hellbent on hiding his decline and allowed a robust primary process to start a year earlier, we'd also probably be living in a very different world. There was an extraordinary amount of hubris involved. Hell, even the amount of time between the debate and Biden stepping down (and then initially refusing to endorse Harris) took an absurdly long time. Felt like the lesson with Hillary's campaign was not learned - they expected people to vote for Harris by virtue she was not Trump. Clearly that has not been working.