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?
Honestly it's bullshit, thousands of dollars of games have died with my brother-in-law, and it's just another reason to pirate everything digital you can.
Don't die without a will and don't die without telling family important details/passwords.