i appreciate you trying to take a reasonable look at this, but you are wrong on both fronts here.
first, nothing stopped the trump campaign from doing the same thing they did in 2016. The innovative work they did in 2016 was to identify pain points and the types of messages that moved people by combining ad testing in facebook with data and information purchased about voters outside of Facebook. Then they ran hundreds of iterations of each until they found the one that worked. nobody had ever been that sophisticated with Facebook targeting before. The problem here, is that they didn't innovate again. Everyone does this now, not just the trump campaign, and dem campaigns had ready access to this same kind of data and testing that allows us to microtarget messages. All the way down to state leg campaigns. Nothing the social media companies did stopped us or the trump campaign from doing it again.
Debates don't win or lose elections. They are a partisan spectacle. They might make one group of voters more excited to vote for a candidate, but unless you absolutely have the worst night of your career, you arent losing based on a debate. I do think trump was bad, but I don't think it was nearly as bad as you are positing. He's never been presidential, the debate didn't change people's minds.
voters rejected the democratic platform across the country last week. But they also rejected donald trump. They had enough, and they didn't trust him to handle the pandemic. Its as simple as that. To be frank, without the pandemic, trump likely wins in a landslide.