I consider the original Dark Souls as one of the best video games ever made (I quit the first time I played it on Ps3). I played it again after playing Bloodborne, DS2, and DS3. And it aged very well. Sure, some parts are clunky, and it is missing some quality of life features found in later games. But it's a classic.
OTOH, a friend of mine loves the series and Bloodborne. The way he explains it, the satisfaction of finally conquering a boss after so many trial and error runs is unmatchable. In a sense, it's similar to difficult games (platformers for me) of the 80s and 90s, or some old school shooters. A slow and steady build-up of skills culminating in mastery. I'd rather do that with something else than videogames.
My take is that I've gotten lazier over time, wanting to enjoy a game for its escapism and relative challenge it provides, but not enough investment that it becomes a chore.
I still remember the moment which I understand how to land a charged greatsword attack to yian kut ku. It's an eye opener.
But yes it's not the game for everyone. It's hard.