Because:
Due to an amendment in December 2018 of the Unfair Competition Prevention Act in Japan, certain gaming-related activities and services have now been declared illegal. This includes:
- Distribution of tools and programs for modifying game saves
- Selling product keys and serials online without the software maker's permission
- Game save and console modding services
As such, sales of products such as Pro Action Replay and Cybergadget's "Save editor" have been discontinued.
It's meant to ban sale of hardware devices and services that allow playing pirated games on Switch and such, but due to the way it's worded it just bans them all.
Personally, I'm okay with Denuvo and other similar DRM when it's used for the intended purpose - to prevent launch day hype piracy. The first few weeks/months are crucial for sales, and I can understand why developers do it.
But after that, especially after the game is cracked, remove the fucking DRM, it did what it could and is now useless, and only makes the experience of legitimate customers worse.