Apart from these, there was the problem with the environment. Souls-like games were not successful from the beginning. They had gone through a period of having very low sales.
From the earliest-released Demon's Souls to Dark Souls, Bloodborne, and Dark Souls 3… all the way to Sekiro; the difficulty level decreased progressively. While maintaining Souls-like games' essence, the game creators lowered their difficulty to cause an increase in sales volume.
This proved that the more difficult games were, the lower their sales volume would be.
What's more, the success of Souls-like games depended on the region.
Demon's Souls went in a direction completely opposite from what was set by the publisher. While researching and developing the game, Miyazaki Hidetaka played some tricks and created the game against the requirements set out to him. Instead, he created a game that fully reflected his own style.