From a design point of view, I think this is the main intention. In various games I’ve played with runbacks, the goal is to give the player some time to breathe between doing that boss challenge, and practice the skills that should be necessary to fight the boss.
I haven’t really played any soulslike game to really make this claim, but it would appear to me that the bosses tend to be drastically different in gameplay than the various enemies you face. The player doesn’t gain any particular skill required to fight the boss in that runback, and this probably is a misalignment in how runbacks tend to work. To incentivize the player instead, the recovery of dropped souls is a whole thing, which can feel like insult on top of injury to many players.
I agree that this entire mechanic is pretty subjective, and it centers around how the player is feeling about an encounter, and their gameplay. It gets into how that death feels too, if the player feels like the boss was “unfair“ it can hurt even more. It’s absolutely a multifaceted problem and I could understand why the developers/designers might want to move away from it, because a lot of the gameplay feels more trial and error than it is pure skill. If you expect the player to re-play a particular section, this is probably not an ideal mechanic to have in. I think it’s best applied in places where you’re trying to teach the player a particular mechanic.