With the sprinkler system in Sims 4 my sims have never died from a fire as the sprinkler always puts out the fires immediately. I have never even had to replace a stove or anything like i did in past Sims games.
I did almost lose a few sims to fire using outdoor barbecues as that has no sprinkler system available - but found a way around that since JA came out and has those cans of spray that puts out fires instantly. My sims tend to use it with out being told if they have it in their inventory. The only thing that ever kills my sims I can't avoid seems to be emotional deaths.