De facto responsibility is a descriptive concept independent of whether there even is a legal system to impute legal responsibility.

Absent a system to impute legal responsibility, this is an entirely subjective question. In fact, the whole reason we have courts and juries is to answer the question relative to the local norms. That's why jury selection is such a pivotal part of the trial process.

Property and contract determine the legal consequence of being held culpable.

They determine the perceived de facto responsibility from the perspective of an outside observer, as well. Law influences public opinion. A country in which smoking is taboo will treat the harms inflicted by second hand smoke as far more material than one in which it is decriminalized or socially encouraged. Same with getting vaxxed/masking up during a pandemic. Or driving while intoxicated.

De facto responsibility is about purposeful results of deliberate actions.

It can just as easily be defined as the neglect of certain actions. But, again, this depends on the social standards of one's neighbors, which are then commonly enshrined into regional laws.