In 2016 Hillary Clinton campaigned by telling voters that the status quo was just fine and she would tinker only a little around the edges. In contrast, Trump recognized that problems existed and voters were angry. (Trump lied about many things, but at least he did tap into the anger, so millions of voters rewarded him.)
Once Trump took power, the entire Republican Party rallied around him with absolute loyalty like a cult’s true believers. Actually, the entire Republican Party really has been very Trump-like for many years (racist ever since Nixon’s 1968 “Southern Strategy” of racism, utterly subservient to big business and contemptuous of the environment and climate, negative toward women’s rights and LGBTQ rights, committed to rigging elections, suppressing voters, refusal to let a Black Democratic president accomplish anything, etc.).
Our nation’s problems preceded Trump. Replacing Trump with a “centrist” Democrat will NOT solve the problems. But Biden’s main campaign strategy is to identify Trump as the problem and pretend that everything will be just fine if we replace Trump with Biden. Biden’s campaign began by saying that without Trump the Republicans would be happy to cooperate with Biden, and Biden wanted to meet the Republicans half-way.
The article at the link below agrees with – and expands upon – what I said in the two paragraphs above. It warns against the assumption that “bi-partisanship” will save us: https://www.dailykos.com/stories/2019/12/26/1907945/-Biden-campaign-s-dangerous-steaming-pile-of-crap-theory?detail=emaildkre
For a much, much more thorough analysis of our problem, read my analysis of the worldview that has been increasingly dominating the U.S. I AM LINKING IT HERE: 2 Replace this Currently Dominant Worldview with the Next Chapter’s Alternative