The confirmation came from the Steam support staff earlier this month when Resetera forum user delete12345 asked Steam support if he can put his Steam library in...
If you cannot pass on your ownership rights to your purchased games to your children, then you cannot pass on your copyright either, I guess?
Agree, even more so with the private cloud data. If your loved one dies and you want to visit multiplayer you created together in open world builders it would be shitty to take that away from them. Eg: Father and son played Minecraft together on LAN server or whatever (If that even is a thing)