At least I can fight Malenia 50+ times without any tedious things in-between. If you die three times at a boss in an 80s game, you’re starting that game over. I would say that if 80s/90s games had similar qol improvements then most of them would not be as hard as souls games.
Yeah, most of the challenge back in the day was clunk, lack of information, and game design derived from arcades, where you had to die so that you'd use more quarters.
It's not that Souls-Likes are hard, it's just death is a mechanic in them. We traditionally associate a death screen as a loss, in that sense you have to redo a section of a game with no additional reward. But in Souls-Like games, death resets the enemies but you can get your lost experience back on top of the newly acquired one. This means that at some point the section should become trivial because you're potentially over-leveled. A Souls-Like can kill the player fast because the return to the point oft death is also fast and rewarding.
That's in my opinion is what makes a Souls-Like a Souls-Like, it's that gameplay is paced with player death in mind.