I'll say again what I said in the other thread:
The issue is that full accounts can be used during that time to harass legitimate players with gold spam etc. Blizzard always got a lot of flak from players for failing to prevent that in D2 and mind you, it was pretty fucking annoying. Imagine WoW gold spammers but 1000x more annoying.
And honestly, if your bank takes 72h to clear the transaction then what the hell?
Assuming everything works as it should, you can start the game by yourself, and in 4 hours or less (time needed to download, install and level to 13?) you will have the full version of the game. In case the payment takes more time to clear, other than the fact that you should first go check what is going on with your payment options, you have the starter edition, which you can continue playing once the payment is cleared.
The other 2 options would be that either you do not have access to your game until payment is cleared, so you start the downloading etc 4 hours later, or that you allow possible abuse in case of payments not clearing. Blizzard chose the middle ground, now it remains to be seen how well that decision will work.
I've honestly never heard of a similar system being used and nor has it ever taken more than a few seconds for payment to get cleared. Is issues with slow payment clearing common in other parts of the world? If all this does is to limit accounts until payment is cleared, then I guess it is not a big problem (for me that would probably take a shorter amount of time for payment to clear than for the game to load). The article made it sound far different.
I never played Diablo 2 online other than with close friends, but when playing WOW, the spamming mainly came from trial accounts at first and then from hacked accounts once they limited messages from trial accounts.