I think there's plenty of people to be mad at, more than enough blame to go around.
Biden could have chosen to be the transitionary president he "signaled" that he'd be by stepping out of the race 6-12 months earlier, and allowing for a full primary season for democrats to rally around a candidate and a platform.
The Harris campaign could have rejected the failed 2016 strategy of courting moderate republican at the expense of blue collar democrats, rather than champion the Cheney family endorsement, in spite internal protests.
I'm not willing to scapegoat just one person for this loss, this was the whole damn team. The DNC needs to realize that people vote when they're excited to vote. That whether they're door knocking or just talking to their friends, the base is going to get those low propensity voters out if they're bragging about some great thing democrats will do. And it's a lot easier when that thing is healthcare or amnesty (Obama), rather than small business tax cuts and a republican bill on the border.
Counting to five, too complicated for voters.