Not necessarily at all. Most do know their killers, but there are “true victim” crimes that happen all the time.
It may “look” like a rage killing because it’s bloody and with a knife— but even knife crimes can be sophisticated, and have a more calculated type of rage, if we were to use that term.
Crimes of Passion which are usually not premeditated, happen a lot with rage in the heat of the moment.
But not all knife crimes are not crimes of passion.
It depends on what you mean by rage? Just the act of being murdered would be considered a victim of someone’s rage, but, would we consider someone who was poisoned an act of rage if they were murdered? Probably not.
But the person slowly killing someone else with that poison could have been so filled with rage and delighted in the fact their victim was slowly fading away. The murderer had rage, but it didn’t really show up in the cause of death… We reserve rage for mass murders, Ax murders, stabbings, etc…
Obviously, Rolling, Bundy, The Night Stalker, BTK, etc… committed horribly violent murders arguably full of rage, but it wasn’t because the victim did anything to deserve it. They had no idea why they were being brutalized… but the killer knows and usually picks a victim (or a place that represents his anger/fixation, i.e. Roger Elliot) and uses the victims as stand ins for whatever it is they’re mad/fixated at/about.