Is there a meaningful distinction to be made between the system and the content?

[Saint-Just]

Really? If I stab someone in the kidneys, or throw a sharpened cream cheese spreader and hit someone in the head, I can't kill them in GURPS?

In my experience death quia death is not that easy in GURPS: even at -HP there is only a chance of death, you need to go down to -5*HP to have "just dead, no roll" result ( -HP here means currentHP = -maxHP, -10 if you started with 10, -15 if you started with 15 etc).

Two factors can account for perceived lethality. First, it's easy to become incapacitated (you don't even need to be down to 0 HP to suffer some hefty penalties, and usually you are not going to have a lot of HP anyway) and whole party incapacitated can mean TPK as we all know. Second, the recovery from injuries due to "natural healing" is looong, and sometimes you still unable to recover fully (that limit on HP damage for hit locations? Kicks in when your arm or leg is mangled beyond use). Advanced medical technology or magic solves the second problem, but not every setting has them.

Finally with (un)lucky rolls there is a probability to do humongous amount of damage with something that's relatively weak. Cheese spreader is probably useless you are rules-lawyering but chuck a heavy glass at someone's head (or a roof tile - ask king Pyrrhus) and you probably have a 1/1000 chance to kill the target if it's human (even multiplied many times over it's far from unlimited - what kills the human wouldn't necessary kill a horse; and depending on how ridiculous you go your mighty-thewed heroes may end up closer in strength and vitality to horses than humans)