Also, why send private keys through the mail (which CAN be intercepted and resent very easily) rather than through something secure like an HTTPS connection?
I am just thinking aloud here - Perhaps it is felt that the private key will exist un-encrypted on the recipients PC or can be stolen via man in the browser malware? In essence, the issue is how to securely exchange a key. Traditionally, key exchanges happen with key encrypting keys which most of the time are PKI public/private key pairs. The crypto private key could be sent by encrypting it with the receiver's public PGP key. It could become technical to setup for the average guy on the street, but I would assume if someone knows how to stake then they would know how to setup PGP. It is difficult to prove that it is the recipient that has the private key unless you have proven identity via face to face. However the same can be said about the physical address entered. This can be overcome by displaying a code at the time of purchase or downloading a text file at purchase time. The recipient then has to encrypt and sign the code/file and upload it back during the session. The seller verifies the code/file by checking the signature of the recipient using the recipient's public key. if it checks out the seller can download/email the crypto private key encrypted with the recipient's public key. The process has flaws but at least solves the issue of the risk of intercepting an emailed key or displaying the key online to be stolen via man in the browser.
Using a physical address on the other hand assists with "know your customer" for anti-money laundering rules.
PS: Seems like this scenario is playing out. Time will tell.
https://bitcointalksearch.org/topic/m.10404932
We have already explored options to do half of the private key online and half from the mail eventually. We are going to change it up, of course, this is only step one to test the system as a whole
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