Why wasn’t this added? Since it’s supported on PS/Xbone.
PS and XB are Power PC architecture iirc if the Switch is propriety Nintendo based, that would be why.
There are differences even between PS and XB: on PS you can move the save between PS3, PS4, and the PSthingy (dammit! must be getting old); XB it’s only one-way from 360 to XB1. That was, apparently, as stipulated by the respective platforms. So Nintendo may have been asked and said ‘no’; or it may have been that the network architecture didn’t make it easy to implement.