However, the technical effort to safely use an XCI (jailbreaking a Switch, avoiding telemetry, finding a clean dump, managing updates) is significant. For the cost of a few coffees, you can own the physical cartridge legally, support Blizzard (yes, despite the controversies), and play seasonal rifts online with friends.
The only advantage an XCI has over a real cartridge is the ability to launch without inserting the card—a convenience that vanishes the moment Nintendo bans your console. The search for a “Diablo 3 XCI” reveals a fundamental truth about Nintendo Switch users: they love convenience. They want the full Diablo 3 experience, offline, without swapping cartridges.
Stay a while, and listen... to the terms of service.