And you're using up resources to do so. The "effect" is not at all the same because the cleric is out of spells until he rests again.
This is wrong. Any flat bonus damage + a decent crit modifier can drop a PC for a good while. (And, armor of fortification aside, if you get crazy with it, it can drop almost any PC throughout the entire game.)
There's also the issue of full attacks. While a monster in 3e is unlikely to drop a PC with a single attack (crits notwithstanding), it has a fair chance of dropping a PC in a single full attack, especially when you consider lots of attacks = lots of chances to crit. A pit fiend does 2d8+13 + 2d8+13 + 2d6+6 + 2d6+6 + 4d6+13 (plus a poison that does 1d6 Con damage) + 2d8+6 on a full attack. Now, a single attack from a pit fiend isn't going to drop a PC, but a few lucky attacks will. When it dies, balor forces a DC 15 Fortitude save not to die from massive damage. Heck, a level one fighter with a scythe is going to do something like 8d4 + 24 damage on a crit.
I think you are mistaking “grittiness” for “deadliness”. In which case, sure 3E especially first level or extremely high level games are more deadly than 4E. But grittiness also encompasses a "low magic feel" and also a feel of attrition.
A balor is something like a CR 18 creature I believe… so yeah you got a creature designed to dish out ~120 points of damage in a full attack (if he hits with all six attacks) to someone in an 18th level 3E adventuring party. Typically if balor rolled extremely well he would hit with maybe four or five of those six attacks and one would be a crit and the damage would wind up being ~120 plus maybe if the players weren’t immune they would have their bear’s endurance enhanced con get temporarily nullified by poison ability score damage. 18th level clerics and fighters can outright survive this. 18th level wizards would shrug off enough of the attacks with stoneskin to survive. 18th level rogues, well, maybe they get hosed but they’ve probably gotten used to it by now, more likely they have taken some sort of prestige class or multiclass combo to survive as well. Even more likely there are some sort of magic items or buffs (armor of fortification, displacer cloak, contingency spell etc) that allows for damage mitigation or survivability. In my experience with 3E, we never made it that high in level anyway. After about 14th level or so, so many combatants were getting killed on a regular basis from disintegrates, death rays, holds, dominates, harms, overlapping fireballs, etc and then getting raised or resurrected after the fight that there was no sense of “grittiness”. Far from it, it was more of an MMO rocket tag feel where people were regularing getting killed or dropped, then resurrected after each fight. I’m not saying that wasn’t fun by the way… it’s just don’t mistake the term “grittiness” for “deadliness”. High level 3E was plenty deadly, and I’ll grant that it was deadlier than high level 4E… but with everyone flying, turning ethereal, hasting, enlarging, killing each other and then resurrecting, readjusting their spreadsheet every time they took ability score damage it took on more of a superheroes rpg flavor than anything remotely resembling a gritty fantasy game.
But those are the outliers anyway. In my longer running 3E campaigns maybe 5% of the total game time was spent at levels 1-3, and maybe 10% of the time was spent beyond level 12 and the other 85% of the campaign was spent at levels 4-12. During that so called “sweet spot” I never experienced characters getting taken from full hitpoints to -10 hitpoints from a monster crit. Yes, it’s theoretically possible for a fighter with a scythe to rip apart a pc, but when the rubber met the road at the game table what we wound up with were ogres and gnolls and gelatinous cubes and trolls and warriors with swords or axes and whatever else in the MM and PCs with full hitpoints didn't get one shot killed by a single monster's turn.
Usually when I see characters go down quickly in 3E it is because of a combo (party gets hit by a fireball in a surprise round, then some poor sucker gets ravaged by two monster full attacks before he wins initiative) and this is no different than the 4E combos of lurker strikes at PC, dazes PC, and then skirmishers gang up on PC to do enhanced damage. In neither game do I usually see a single monster drop a single pc in one round unless there are spells or some save or die attack is used.
Unlike 4E, 3E did have those save or die effects, but by the time those were common, then very high level magic was involved, the party was flying/invisible/teleporting/enlarging/hasting/scrying/find the path/commune/scry and those high level magic effects (either by a high level spellcaster or a fighter or rogue outfitted with hundreds of thousands of gp worth of magic items) cancelled out any feeling of “grittiness”.
In some combat ways I suppose low level 3E was a little grittier than 4E, but in non combat ways I found 4E to be grittier overall… the default setting in 4E was points of light, where there were a few havens but most of the world was savage war torn monster infested wilderness, and the lack of divinatory “I win” investigative utility spells and the severe nerfing of fly and invisibility made for a more “lower level” feeling game world even when the players were in their low teens in levels. While a first level 3E game felt maybe a little grittier than a first level 4E game, a 12th level 4E game felt much grittier than a 12th level 3E game. Third edition was a little more deadly and fourth edition was a little bit more “low magic” but deadliness and low magic alone aren’t the sole components of grit. I think it all pretty much cancels each other out, and both systems I would still classify as “non gritty” systems, unless the DM specifically emphasized it in his choice of settting, adventure goals, and house rules.
As for healing… those CLW wands really are a game changer. I think because of them (I use them and you don’t) we have totally different frames of reference. Which I’ll discuss in my next post.
TLTR
Grittiness encompasses deadliness, low magic feel, and attrition based gameplay.
3E is more deadly than 4E
4E is more low magic than 3E
Neither is particularly deadly or low magic RAW
CLW wands have a direct impact on the level of attrition.
