The issue with any hybrid system is you have to play the incentives out at scale.

E.g. if blame is assigned when there's a written guarantee, why would anyone ever make a written guarantee?

And not trying to be obtuse, but I've only ever seen blameless cultures work in absolute. Compromises let back in all the nasty mal-incentives you see driving unproductive CYA behaviors.

E.g. Some people with lower amounts of credibility will be eager to make guarantees in writing, if they want to sound more convincing than someone with higher credibility who disagrees.

Something like a new engineer disagreeing with a PM, a PM disagreeing with higher management, etc…

There’s many reasons why that would be a favourable choice.