I think bloodborne holds a lot of reverence because of the themes it portrays. Besides Sekiro, which also has a cult following, all the other Souls games are based in and around medieval fantasy of some sort.

Bloodborne starts in Victorian England with a Van Helsing story and the descends into Lovecraft really fast. For a lot of people, myself included, that’s inherently a more interesting setting than medieval fantasy, which you could argue is more of a baseline fantasy setting.