Sekiro is legitimately hard.
What I find hard to comprehend is people being mad about abstracted combat systems that include a chance of failure. It's not bad design, you can't just always succeed to maintain some internal logic in the system.
If you think I dislike that system because it makes games hard you have no idea what you're talking about. I love hard games, and I play pretty much everything on the hardest difficulty available if I'm experienced in the genre. Games with this kind of mechanic tend to be easy these days anyway, not the opposite, JRPGs are an example of that.
Failing because RNG is not a game being hard, it's a game being bad. When you can't do anything to prevent that bad RNG the game is as brainless as if it was easy, it's simply more punishing. This is why in Fallout I don't mind it as much. When you start the game you can choose one of the weapon skills as one of your main ones, and it will make you barely miss if you combine it with good perception.
On the other hand, Pillars of Eternity doesn't really offer you anything to overcome this problem on its hardest difficulty. I put 17 points on Perception and I was still missing a lot. It's just dumb. I could maybe tolerate this when I was younger, but now that I'm 30, losing against a boss or whatever because the game rolled a number instead of another (and not because I made a mistake) is not something I want.
Another example of bad game design is being attacked from behind when the game is not designed for that. SMT Noctune on its hardest difficulty comes to mind. When you get to the world map every enemy is stupidly strong (because the game was never balanced around that difficulty). If you get attacked from behind it's 100% an autolose even if you start the fight at full health, you die before you get a single turn to make any decisions. That's bad design, not a game being hard.
Mentioning Sekiro is especially nonsensical since every Soulsborne game is extremely fair to the player, and you can beat anything with the right amount of skill and understanding of the game mechanics, without the game suddenly deciding for you that this time you will lose because of RNG.