I do think the subject is interesting Elegran
As it pointed out in the article, after someone dies their effects -photos, stuff they have written etc, forms part of their estate and can be accessed by and shared out among the relatives.
That isn't so with photos that have been posted online on social media sites, or things that may have been posted on Internet forums.
I thought Facebook's response to the mother in your link sounded quite uncaring, but possibly they took legal advice, that it breached confidentiality to alter someone's privacy settings after their death. Presumably it has not been tested in court.
As far as online bank accounts go, it doesn't seem to me to be very different from any other account - you may have the passwords to allow you to gain access, but it's illegal to do that unless you're the executor and probate has been granted.
If we open an online account that our DCs know nothing about, it's not so very different from hiding large amounts of cash in the house and not telling anyone where it is.
After my mother died, an aunt told me Mum had hidden some money in the cooker, but not until after said cooker had been disposed of!