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in case of steam don't count on this!
in germany (where i live) tos doesnt count too (any text presented AFTER i paid is nothing), but if steam sees someone selling his account they just ban him regardless.
they argue that you did NOT buy the game: you just lend it.
i've not yet seen someone buying a dvd, register it through steam and tries to sell it. if he goes to court he might win (but ONLY if he did buy it in a shop - NEVER for games bought in steams online shop page, because they clearly state they only lend them out)

bought in store (online shop in austria, shipped to germany), had to register via steam in order to play it, wana buy it?
Im not actually going to sell, because its key would allow you to change the mail and password to my steam account. Steams ToS is unbelievable in that regard.
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In the case of an account, the person who originally owns the account is blamed if the buyer is a fraud.
Which is complete and utter nonsense. Why would you blame someone for selling their account if the new owner does shenanigans with it?
If you find it nonsense, then I'll need to tell PayPal and other websites as well that their TOC is utter nonsense right?
Im not sure what you want to tell me here. I dont care if you tell paypal their ToS are utter nonsense. Their employees probably agree after a few beer.
I am not only talking about bitcointalk accounts but also about all those accounts of websites that find it illegal and against their TOC.
Again: If its illegal you can report it. Im just not sure we have the same understanding of illegal.
For eg: If anyone gives their house on rent (which is legal) to a wrong person, what would be the outcome?
I assume you are saying: I have a house and let to a criminal. They signed a proper contract and all paperwork is correct.
Not only the person who was staying in the house will be blamed but also the person who owns the house. You will say that the owner has nothing to do with the crime but without any verification, selling/renting anything is considered wrong.
What? Where do you live? If I go and start burning down cars in my hood tomorrow, why would my landlord be to blame?