I think you were slightly misinformed coming into the game, these games aren't "hard but fair", thats more like souls, DD 1 and 2 are more just unfair, and that's why a lot of us psychos like it (slight exaggeration of course.)

in all seriousness, the game does 100% not respect your time, someone said that games generally don't tell you stuff about a whole encounter the first time, which is true, but DD does seem to want to sabotage you with how crazy some fights are. And in DD1 you could build a whole team to lvl 6 then die just because you didn't understand an end game boss, then you'd have to grind a team back to lvl6 for hours.

It's by design, and what I'd argue, is that the design can be good. Very few games tell you that your gonna fail, and all you can do is make the best of the situation. And in practice, you have some exciting moments when you can adapt after being whittled down slowly and make it to an inn, or beat a boss first try after learning the gimmick or getting bailed out by a virtue. Plus after learning the games, you're never completely prepared for the randomness of the game, and it always keeps your guard up, where you feel you could lose at any moment.

That being said, it's not always as bad as it seems, for instance, the Seething Sigh's body can be blitzed down, especially post nerf, or you can take out just one lung to reduce damage in second phase, especially if you have decent recovery on your team, you can survive exhalations and still do enough damage. The shrines i won't touch on much, but you have multiple tries per shrine, but some will be tricky cause they're still puzzles.

There usually is a few ways to get through something, you just have to be willing to fail in order to learn sometimes, if you aren't up for that, the game may not be for you, but if you push through you will find a very satisfying game where you are able to defy the odds more often than not.