The decision to develop Diablo 5 as a standalone title, rather than an expansion for Diablo 4, was driven by the sheer ambition and scope of the project, according to Blizzard.
Production Director Tiffany Wat and Executive Producer Matt Zitterman explained in a recent interview that the vision for Diablo 5 quickly outgrew the confines of an expansion. The team's creative direction and the technical advancements they aimed to implement necessitated a new foundation.
While an expansion for Diablo 4 would have allowed for incremental additions and refinements to the existing game, the developers felt that the new ideas and the desired evolution of the Diablo experience required a complete reimagining. This approach ensures that Diablo 5 can fully realize its potential without being constrained by the architecture or design limitations of its predecessor. The announcement timing was also deliberate, allowing the team to communicate their vision and the reasoning behind it, managing player expectations for the future of the beloved franchise.