Actually a really solid idea. You can basically guarantee that the accounts linked to the jsp are all right and true, as it would require the same kind of two-factor authentication actions from inside of, both, the jsp and bnet account in order to create the link. This way, everyone can be sure that they are not being impersonated and that fewer falsified scammer accusations will result in innocent people being locked.
As an aside, this would also be really integral when making trades in games, such as World of Warcraft and others, wherein you will be almost insta-banned if you mention d2jsp or give any in-game indication of rmt/third-party trading. With linked accounts, people can be sure the person they're trading with in-game matches the person they're communicating with on jsp.
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Make sure to add a poll to this so we can vote!