Why don't Blizzard want to make cross-platform for offline saves?

Blizzard isn’t the problem here. The D2 character files are exactly the same on PC and console, and they are cross compatible. However they are encrypted on console, and more importantly Sony and Microsoft don’t allow you access to your save files. If you could access your save files and decrypt and encrypt them. Then they would all be cross compatible.

As far as I know, it’s only possible to do this with PC and PS4