The biggest problem with the first debate was small-d-democratic
The first debate between Trump and Biden was chaotic and barely a debate at all. The fact that Trump came out swinging as he has against the press and anyone willing to criticize him ever since he started running in 2015 was not surprising, what was surprising was the extent to which he went all-in on this flawed strategy. It showed how little room he has to play with and how few real accomplishments he has to boast about. He tried to make Biden crack because if this election ends up being a referendum on Trump, he’s toast.
During the very few moments that Biden actually got to speak, he did well, he was coherent and he certainly cleared the very low bar that Trump had set for him by calling him senile, sleepy, mentally deficient, and unfit for office. He spoke directly into the camera on several occasions, putting one of his major strengths, his empathy, to good use.
When muting someone’s mic isn’t an option, there isn’t much more to do than what Biden did unless you want to get down and dirty in the mud which usually doesn’t end well for mud newbies.
The moderator, Chris Wallace of Fox News, said beforehand that he wanted to be invisible, but that doesn’t really work when you’re moderating Trump. Without the power to mute their mics, it becomes hard to moderate at all since Trump wasn’t going to abide by any rules regardless of how much Wallace yelled at him. Wallace could have yelled more and been more forceful, absolutely. But would it have made Trump follow the rules more than he did? Unlikely.
Trump probably didn’t gain any voters during this first debate. The gap between the candidates is still pretty large and the debate probably didn’t help Trump with the few truly undecided voters that are left.
Trump’s refusal to condemn white supremacy also tracks with his comments after Charlottesville and other things he has said while in office. That doesn’t make it not noteworthy though. It just means that he still hasn’t changed despite all the hot takes about “Teleprompter Trump”.
The biggest issue is probably small-d-democratic. Those who don’t follow politics, which is most people, might have tuned in for a few minutes and immediately been turned off because what they will have seen was not pretty. The biggest bloc in American politics is not Democratic or Republican. It’s non-voters, which is a problem for any democracy, especially for one of the world’s most important ones.