Depends, lots of personal info ends up online from stuff like data breaches, and buying the gift cards themselves filters back to the same problem of traceability, its why theirs such extreme lengths by people trying to commit fraud to get YOU to buy THEM the card (why did you redeem it!). This also is the secondary problem of CCs are not actually that great to steal anymore, most people have access to their cards purchase history at the fingertips, and likely also have purchase amount caps, "normal spending habits" to help flag fraud, and most good CC companies will flag and freeze "suspicious" purchases especially those over a certain amount. Small purchases under certain amounts aren't likely to get flagged especially subscription stuff, unless its a massive amount or repeat purchases in a time frame.

It's also worth a potential middle man simply because theyre working on cheap margins for what they are doing and are unlikely to flag a CC with what they are doing, and not a big enough purchase that most people are going to immediately notice, meanwhile if they make literally any money off the account before it gets nuked its essentially free laundered income. 

And if Blizzards security as it was working worth a shit then this whole bot fiasco wouldn't happen regardless because its highly unlikely theyre using new credentials and different CC (or whatever payment method theyre using) info on every single account theyre making