> I feel like I've watched outsider-y progressives get elected into prosecutor roles and then fail their constituencies not because of ideology but over basic competency issues

Huh, I went through a similar journey in New York, starting as an advocate of criminal-justice reform and then getting fed up with the incompetence.

And while I wouldn't say ideological inflexibility is ideology per se, one of the contributors to ineffectiveness I saw in New York was a simultaneous inability to tolerate competent people with even slightly-divergent viewpoints (and there were a lot of red lines–I don't know what multidimensional beast could thread them), or, alternatively, an inability to fire or beach clearly-incompetent people because they were part of a priority community. (Read "community" broadly. It might be an identity. It was more often whatever union or local progressive club the person cropped up through.)