People aren't going to maintain such lists individually. So you'd want some central operators, like the antispam DNS services. But then they have to decide what counts as "stolen". Ordered something and then claim it doesn't arrive - who do you believe? You're back to the paypal situation, except rather than reversing transactions you're declaring bitcoins "stolen".
Not to mention the difficulties of running a collaborative central operator in a community of radical individualists.
People aren't going to maintain such lists individually. So you'd want some central operators, like the antispam DNS services. But then they have to decide what counts as "stolen". Ordered something and then claim it doesn't arrive - who do you believe? You're back to the paypal situation, except rather than reversing transactions you're declaring bitcoins "stolen".
Not to mention the difficulties of running a collaborative central operator in a community of radical individualists.