But if it was compromised on that network, wouldn't that mean exactly that its security failed?
No.
Some gullible fool falling for a phishing scam is not Micro$oft's fault.
I can't believe (yes I can) that you are equating Sony's entire network getting hacked to dumbasses who willingly give away their private info to phishers.
What about you JLA? Did you attach your credit card to your XBL account?
I paid for my XBL account using funds looted from the local SEIU slush fund.