That's a fair observation. Though, while they may play that way, it doesn't necessarily mean it wasn't unintended from a design perspective.
With more naive designers I'd definitely agree. But I feel like the core design of 5E (only the core, not optional rules etc.) the design is tight and there's relatively little naive about it, and Perkins/Crawford seem really sharp about this kind of thing. I'm pretty sure they preferred whack-a-mole to the alternatives. Which isn't to say alternatives aren't valid, but I don't think it was an accident of design in the way so much was 20+ years ago.
Dead people don't breathe. Unconscious ones do. Doesn't seem that hard. Especially given 5e's hyper combat awareness that's already provided.
I don't, for one second, believe that, in-fiction, a warrior can see whether someone he just downed, who is likely covered in armour and robes, and possibly in bad lighting conditions, or with bright flashes from spells, and so on, is breathing or not, in far less than six seconds. It's hard enough to tell in real life that people take special measures to check if people are alive, like checking pulses, fogging mirrors, and so on. And you have to be able to do this whilst being under attack yourselves. Humans are remarkably bad at telling if people are dead or not.
I mean, if you could tell just by looking, emergency services and so on would have a hell of a lot of an easier time, soldiers would never miss people playing dead or merely unconscious (which IRL, happens routinely - and also is a fantasy fiction trope)
So I don't at all agree that in-fiction it works for
normal mortals to be able to tell this.
Personally I'd rule that it'd be an Action, and an Medicine check to determine whether someone unconscious was dead or not, in-combat. Out of combat you can check if they fog a mirror or something (if it's cold enough), or listen to their chest.
That doesn't mean no enemies should know. Undead probably often should. Some other supernatural beings too. Beings with incredible hearing could probably make Perception check to hear if a heart was still beating, but that might be an action, given it's in the middle of an extremely loud battle full of shouts, explosions, steel clanging on steel and so on. However, they wouldn't need to get next to a dude.
I do appreciate that there is an asymmetry here, in that PCs rarely attack downed enemies, and enemies can't be healed up because they're dead but I'd suggest the way to correct that asymmetry was to modify enemies so that if there was a healer present, you tracked Death Saves for them too (or maybe just do it generally).
I'm not so sure. Just as an example: A level 3 fighter with plate and defensive style can take about 3 times the punishment that a level 3 bard can take and that's before adding in other abilities that can mitigate damage (2nd wind, battlemaster parry manuever, samurai temp hp, etc). The only unresolved variable is how many enemies go for the fighter vs go for the bard.
I think you might want to consider that further. Yes, a Fighter with maxed-out AC taking only AC-based attacks can indeed take a much larger beating than a Bard.
But plenty of Bards are melee. Valor and Sword for example. And they don't have good ACs. They don't have tons of HP.
Likewise Rogues. Bladedancer Wizards. Clerics who don't have Heavy Armour proficiency. Some Druids. Bladepact/Hexblade Warlocks. A lot of Rangers. I could go on. You're comparing a best-case scenario for melee survival against a middle-case backliner. But that backliner could be a frontliner and all he gained was Shield and Medium armour, no HP, no Defence style, no Plate, no manuevers to prevent damage (well, Sword does but it's quite limited).
Do you see what I'm saying. Yeah, actual tanks are probably going to still tank, so long as they catch the odd heal. But any melee who isn't a tank? They're likely to be a very bad choice to play if you like surviving combat.
I've played death at 0 hp games and even in those we didn't feel forced to have a healing character. Typically if your melee you have damage mitigation abilities. Those go a long way. You can always take the dodge/dash/disengage action if you get low on hp or use a class feature to help. Even monks tend to be fairly tanky when you use the bonus action dodge ability regularly. You also tended to build a bit more defensively overall which resolved alot of the 'glass cannon' issues.
Yeah, YMMV, but mechanically, "live" healers who can put out large amounts of in-combat HP will suddenly jump from "nice to have" to "hugely advantageous", to the point where if you got through the same adventure with the same five PCs, except in one they have a Life Cleric, and the other they have, say, a Loremaster Bard, or god help us, a Valour Bard, the Life Cleric party will likely have a laughably easier time.
But I agree, people will build more defensively, and use defensive stuff more, for sure.
Even damage falls in that as killing enemies quicker makes you less likely to die. But I'm not sure how quoting a list of pretty much every combat related ability becoming more valuable makes sense - what are they becoming more valuable in relation to?
In relation to damage-dealing abilities, especially ones which don't tightly target damage. It's true that faced DPR declines as you drop enemies, but what's a somewhat facile comment here, I'd suggest.
You're creating a situation where never getting downed has a much, much higher value. Thus all the defensive combat abilities have a higher value - significantly higher - if you don't have live healing, they increase even further. In a lot of cases, DPR is just not going to save you, because enemies in 5E often take a while to get down (HP pools on enemies typically being far larger relative to damage they output than in 1E/2E/3E, even considering changes in PC damage output). Burst damage also suddenly becomes more valuable. Right now, you don't have to build very tightly, because overall, a "Ceramic flamethrower" (a less extreme glass cannon, shall we say) who steadily puts damage on the enemy but isn't very tough is pretty useful (this includes a lot of casters), as is an actual glass cannon, as is a tank or whatever. By attempting to kill every PC who hits 0 HP, now you refocus things so that it's best to burst down what you can as quickly as possible. Ceramic Flamethrower types who spread damage around will be bad choices. You want intense, targeted damage, even at the cost of a lower overall DPR, because your focus is on not being killed and thus out of the entire adventure and forced to re-roll, and depending on the DM and scenario, maybe not even able to join next session, maybe having to wait multiple sessions to play again (this is mitigated somewhat with revivify etc. of course).
Which brings me to another point - Revivify becomes hideously vital unless you like re-rolling. Now thankfully, Tashas made it a lot more available, but that means you pretty much have to have a Cleric, Paladin, Artificer or Druid in the party, and for them to hold on to this spell. Bards don't get it, even after Tashas, though in this game I imagine most Lore Bards will make it one of their cross-class spells.
Which brings us back to the live healer/specific comp situation. A party with access to Revivify can have someone die, get them up after the battle, and just rest or whatever and continue. A party without that is down an entire adventurer, depending on the DM, for potentially the rest of the session or multiple sessions. That may simply make a lot of adventures impossible to complete, or force retreat, and if you have a clock-based adventure, the prince gets sacrificed to the dark gods or whatever. It also creates a death-spiral effect unless you modify encounters ahead, which I'm guessing isn't something that goes with this.
So that's the next big consideration for me:
5) What happens to the PCs who die and what does their player do, esp. if you don't have Revivify available? Are you a DM who just lets a new PC turn up in an action-movie-ish way? If so, probably this doesn't cause a big problem. If not, then you have death spiral issues and adventures derailing entirely, which may be totally fine, of course, but you asked about the impact, and that's an impact.
