[walrus1066]

'Mostly though, I think software developers just need to do better work, and stop blaming the project management for their own inability to deliver good work in a timely manner.'

Even if this is the case, PM still responsible for blown deadline, because they did not estimate their teams delivery velocity correctly.

They should either:

a) give longer estimate, if their team quality is low.

b) pay more to hire better, more productive developers.

A good PM will also account for uncertainty in devs estimation, by padding etc

Predictability of delivery is what ultimately counts, not giving optimistic deadlines.