Yeah, that’s the history of the game.
5e’s death rules are as follows:
If you get hit an drop below zero, you don’t die as long as the extra damage doesn’t exceed your max hit points.
So… unlikely past level like 2 or 3 with a bad crit. Add in the following problem: any damage healed when you’re at zero heals from zero and there are no side effects.
Example:
You’re a 15th level wizard with say 86 hit points. You get meteor swarmed for 100 damage. You fall unconscious and will maybe die in 3 rounds if you roll poorly on death saves.
Your cleric casts a Healing word, healing you for 16 hit points. You are awake and fine now.
You get hit by another meteor swarm for 100.
He casts healing word next turn for 7. You’re fine.
To die you need to go down and then fail 3 death saves (roll under 10 on d20). If you make 3, you stabilize. If you roll a 20, you wake up and get a hit point.
If someone beats you with a club while you’re dying, you lose 2 death saves. Any other damage does 1 death save to you. They don’t carry over or anything. So you can be cut down, stabbed in the head and get back up and repeat forever. A first level cleric can keep up a level 20 character against basically anything that doesn’t have 3 or more attacks by healing 1 point of damage. Paladins can in theory do it… for like hours by healing 1 point with lay on hands each round.
Meanwhile in the old days, -10 meant you were dead at level 20 and in the old, old days 0 meant you were dead at level 36.
Also stuff like Orb of Annihilation does like… nothing. Its like 2d10 damage per round you let it molest you (it moves slightly slower than you can crawl). Instead of, you know, instantly annihilating you as per the name.
I kind of agree with Armando, though it’s a HELL of a lot easier to make a character in 5e. There are just a lot less options. And they do some great stuff with multiclassing casters and the like. It just feels… like all the corners are rounded and everything is kind of made of foam wrt RAW. Of course almost no one plays RAW, everyone houserules things to be deadlier and more interesting. Critical Role is the biggest D&D push in decades and they houserule ressing with rituals and whatnot so that it matters. And Matt has no problems beating downed players. His monsters tend to commit. His dragon is mad at you, he’s full attacking you. Bad news is his bite dropped you, so now you’re getting 2 claws with advantage… you’re gonna die.