When Dark Souls came out it was pretty unique

I wouldn't argue that it was unique. I'd argue a lot more that when Dark Souls came out around the same time in the greater context of the US/EU markets a good majority of well known devs at the time were going pretty hard into this weird idea that they need to capture the casual audience by making their hard games easier, and also a lot of japan devs at the time were going very hard into making their games more westernized for the western markets (which also involved making them easier so...). And Dark Souls came out and really wasn't doing any of that, so I would say that the reason why Dark Souls took off the way it did is simply that a lot of other devs were shitting the bed at the time.