Our actions either regress to prior causes and we are ultimately not responsible for them (you didn't control the circumstances of your birth or upbringing), or randomness inherent in a chaotic system; and we can't be held accountable for randomness either.
I'm not sure what precisely "can't be held responsible/accountable" means practically.
A white-tail spider might be a purely deterministic biological machine, but I'm still going to either squash it (or if I'm feeling merciful, catch it in a jar and toss it outside) if it comes into my house. Because I know its behaviour is likely to injure me; I don't have to "hold it responsible" for its behaviour in some moral/spiritual sense in order to extrapolate its future actions from its present state, and intervene.
A botnet on my computer certainly is a completely deterministic machine, with not a shred of agency or accountability, and I'm going to squash it even harder than the spider and with even less regrets. I don't consider it to have any kind of moral responsibility - but I know that it's a thing, that exists, that has an inside and an outside and that its inside includes certain predictable behaviours, and that those behaviours are hostile to my interests, and I'm going to recognise it and judge it not for its metaphysical stack-backtrace but for what it is right now, and what it will do.
Why do we need to have any idea of moral "accountability" before we can judge and act on another human's behaviour? Inferring their current state from their past actions, and predicting from that state their future actions, seems to be enough for all practical purposes.
Granted that humans do have the ability to change their behaviour toward other humans, which to me is the entire point of not being hash and hateful in our justice system; I'm in favour of forgiveness, but "they're not responsible for their actions" doesn't make any sense to me. Criminal justice is a clear-headed pragmatic matter of preventing people from doing bad things in the future - or becoming a cause of bad things in the future by way of inspiration - not metaphysical retroactive assignment of ultimate blame. Isn't it?