There were enough Republicans who voted for Biden in '20 to flip Georgia, which is solidly "mainstream" Republican (e.g. Reagan Republicans).

The article's analysis of why Hillary lost is correct, and the diagnosis of the failures of Clintonism is also correct. They fail to point out that Clinton "won" '92 because Perot pulled away enough Bush votes in enough states to swing the Electoral College to Clinton, who only got 40% of the popular vote. That "victory" somehow convinced a bunch of Democrats that conservatism without bigotry (or at least less) was the key to electoral success. Clinton got reelected with the power of incumbency and BobDole being a fairly weak candidate. That cemented the conservatism lite in the Democratic Party for a generation, many of whom are still in the party.

It's changing though. Biden is not a classic conservative Democrat anymore, or at least his team and policies aren't.

One big thing they need to do is acknowledge that the system is rigged against the non wealthy, and that small-d democracy as it exists today in America is not up to the task of helping the non wealthy. Then they need to propose ways to fix our broken democracy, ask young people for suggestions for how to fix it, and write some binding policy proposals to implement those fixes.

Because right now Trump and the Republicans are acknowledging that our democracy is failing non wealthy (straight white Christian) people, and the solution they're offering is to do away with it entirely in favor of Hungarian or Russian style authoritarianism.

The first part of that message will resonate, and the "help us fix democracy" part needs to be the 2nd half. Or Trump probably will get reelected.