What happens if bitcoins are purchased with a credit card? Who will be responsible for the chargeback in that case? Coinbase?
In theory, a bitcoin exchange should have a near-perfect defense against chargebacks for faulty or missing products or similar, by showing via the public block chain that they delivered the purchased product as requested. However, there's no defense against chargebacks claiming that the cardholder didn't make the purchase (stolen card number, etc).
Bank wire transfers, though, are unable to be reversed. Its a pity that most US banks charge for them.
1) They have to explain to the credit card chargeback authority what a bitcoin is and why the entry in the block chain means they actually sent the coins.
2) Nothing to stop the Bitcoin buyer from just saying "I didn't do it" (Which is 'friendly fraud' in the article).
From my experience, reversing a chargeback is only possible in a minimum of cases when sending physical items, and even harder for digital goods that you can't just send again (Bitcoins vs an Ebook).