And since leveling up doesn't actually make much of a difference in Souls games compared to getting better gear
Eh? Each level up gives you an automatic boost to defense in all but DS2. Twenty level ups gives you a huge boost to defense. That's in addition to damage or HP or whatever else you may choose to boost.
True. However, in the earlier Souls games especially, health and defense only make a big difference to a point. Every boss fight in a Souls game is
vastly more difficult when it's capable of one-shotting you with an attack; but once you're safely past that margin, your total health doesn't matter that much. This is because, once you're past the very early game (or have the Rite of Kindling in DS1), it's pretty rare to actually survive long enough to have actually ran out of Estus - the way you mostly die in a boss fight in a Souls game is when you screw up the timing when you try to heal. At that point, the thing that will
really make the fight easier is being able to do more damage, because it reduces the length of the boss fight and, consequently, the amount of time you have to hold on without screwing up. This goes double for the fights in which you fight multiple opponents, which usually the most difficult Souls boss fights anyway.
Bloodborne, I should point out, has a somewhat different dynamic in this regard. Some of the harder bosses (mainly the ones from The Old Hunters) have a
lot of health, while you're never really prevented from healing, so it's entirely possible to lose a fight because you run out of health vials. In that case, increasing your defenses, and more to the point, Vitality is actually genuinely helpful - particularly so since vials heal a percentage of HP. This being the case, leveling up
does gradually make boss fights easier in a substantial way. That doesn't apply to the other Souls games, though, which is pretty much exactly as intended - you're not meant to get a big power boost by grinding for souls, the stat system is there to allow for different character builds and to let you gimp yourself if you want a challenge. To improve your character, you're meant to go explore areas you haven't been to yet.
Getting better gear? Gimme a break. Getting a better weapon boils down to upgrading....whichever weapon you want to use. Which involves, yes, grinding the same exact monsters standing in the same exact places in the same exact levels near the same exact bonfire. That is an aspect of early Souls games I don't have any nostalgia for.
Dark Souls isn't Final Fantasy. There are no uber weapons waiting to be discovered. There are some good armor sets, but in Das1 you get Havel's before Ornstein & Smough during normal course of exploring that level and its secret room, and you need to be high level to even consider using the set. And it's worthless in that boss fight anyway. So what do you do if you get stuck?
Or what if you get stuck on final boss or optional super boss? You can't even upgrade your weapon further at that point. In Bloodborne, with gems you can.
This would be a better point if the chalice dungeons were a good place to acquire gems or materials, but they're not. Near the endgame, you'd be far better off farming Winter Lanterns in the Fishing Hamlet or in the Nightmare of Mensis. To get gems better than those in the chalice dungeons, you'd have to have gotten through bosses that are vastly stronger than the final boss, so I fail to see how that helps the average player who is stuck, particularly since those gems are such rare drops that trying to get them is a far more tedious alternative than finding them in the normal game. The best use I can see for chalice dungeons is that they're an OK way to scrape together some blood echoes if you need to buy vials or something, though even for that, I think doing co-op is generally more fun and gets you some Insight as well.
Having said that, the difference between Bloodborne and Dark Souls is that in the latter, while getting
better equipment still mostly requires upgrading your weapons, you have a much bigger and more varied arsenal to build a strategy, which, of course, you build up by exploring the game. In the early game especially, getting your first really good shield, getting armor with poise, getting the Wolf Ring, getting spells, getting a decent bow - these are all things that allow you to approach problems in entirely new ways. The Drake Sword and the Astora Straight Sword are really great in the early game too, and the Lighting Spear from Sen's Fortress is quite sufficient for Ornstein and Smough. Of course, it's still a difficult fight, but at least you can improve your odds by trying out different strategies (if all else fails, use Pyromancy). And hey, if you still can't get through, you can get a co-op partner. It's nothing to be ashamed of. Well, maybe a little. Not much, anyway. But even if it was, exactly how would it be worse than getting through by grossly outleveling the content?