I’d have to know a lot more about DID before I’d feel I could say much about this.
However it occurs to me that non-disorder-level dissociation is extremely common, and is very common as an ego defense mechanism to avoid facing the many perpetrations people inflict upon each other.
And it seems to me also very common that dissociation may be a very common mechanism for coping and enabling perpetrations, AND that there might tend to be many people who develop dissociative disorders (again, I do not know the technical definitions or legal requirements) as a result of a saner choice to do something terrible to others.
Then there’s also the question of what society and lawmakers consider the purpose of the law and penal systems to be. In the USA, many people see the law’s role as punishing and locking up perpetrators, whereas in e.g. Norway it may be established that the goal is to heal and rehabilitate perpetrators.
Also, in the USA, the calendar may show 2020, but many people have such views as being pro-death-penalty; see convicts (or even suspects) as nearly non-humans who should be punished, confined and/or killed; and/or are fixated on the idea that criminals get off too lightly and easily too often based on what they feel are bad reasons (including insanity defenses, even though the actual results of an insanity ruling may end up being rather worse for convict than a guilty verdict would have been).