Welcome to the 70s and 80s where there was no such thing as savegames for the most part and you got 3 deaths before starting over. This is no different. A boss is just a level of sorts. You learn the mechanics and then you beat the boss and move on. Do it enough times and you can do it in your sleep. People have been playing ridiculously forgiving and easy games where there's no cost of failure so long that they don't even know what a merely challenging game is.
Difficulty systems in the 70s and 80s were famously for eating quarter rather than based on any actual game design philosophy. Not exactly a comparison I think is worth making.
The "just learn the boss" argument is also somewhat frustrating given how frequently there are long ass walks back from bonfires to boss doors. Dying a bunch to learn the tells and attack timings is much less attractive when it takes minutes to go from a death to your next attempt. Compare this to something like Hotline Miami where you are playing again instantly. Much better option there.
Welcome to the 70s and 80s where there was no such thing as savegames for the most part and you got 3 deaths before starting over. This is no different. A boss is just a level of sorts. You learn the mechanics and then you beat the boss and move on. Do it enough times and you can do it in your sleep. People have been playing ridiculously forgiving and easy games where there's no cost of failure so long that they don't even know what a merely challenging game is.