And I'd say my point is that the Web sites ARE responsible here. Then can prove they fulfilled their duty of care re your wealth, but in many cases it sounds like they haven't.
I do get the point you are trying to make, but I don't really think you are right in this particular case. Blockchain.info web wallet is not a custodial service; they are not holding you coins for you, but rather providing an interface in which you can handle your coins (with your private keys). If you are using a Hardware wallet (say trezor or ledger) to keep your coins safe and also use their app/interface but somehow end up losing the coins; is it your fault or is it theirs?
As for the rest, every big company does usually get a pass in the old legal system, only thing that matters here is cabbage; so OG crypto services like blockchain (or some exchanges) have no real trouble in this department. Sad, but that's how the world is currently run...