Walk me through it: in order to get dictators killed, because they defend themselves very effectively, we should put everybody on the planet under a biological death sentence, which will get the dictators too.
No, I cannot endorse this.
No, I cannot endorse this.
So at least two systems run better with the implicit time limit.
Besides, maybe it's the young people who are the most dogmatic. Studies are inconclusive: https://en.wikipedia.org/wiki/Planck%27s_principle#Rebuttal If we're going to go around killing people for having rigid ideas, perhaps concentrate on the young ones, for statistical reasons.
* Undoubtedly sometimes the spark of malevolence develops into more coherent and sophisticated badness, I have to admit, so an old person has had more time to mature into being truly terrible. But this is against the pressure of rationality.