> It's all layers of porous defenses.

Also known as the "swiss cheese model" in risk management.

part of why rexec is "historical" is that Guido was looking at some lockdown work and asked (twitter, probably?) the community to come up with attack ideas (on a specific more-locked-down-than-default proposed version.) After a couple of hours, it was clear that "patching the problems" was entirely doomed given how flexible python is and it was better to do something else entirely and stop pretending...