To be fair she was asked in an interview how she would differ from her predecessor and she totally choked. It was like she'd never even considered that was a question somebody might ask her. She just didn't have an answer.

She might've been a fine president and she might've actually changed some things. But even more fundamentally than whether she would've changed anything, Harris was a lousy campaigner with an ineffective track record as a politician. As you point out, catching a former prosecutor flat footed with an easy interview question is inexcusable. A last minute shove to the top of the Democrat ticket was burdened with all of that downside from the very beginning.