Hmm, I'm not sure I'd call 5 solid hours of grinding in order to afford one single car "everything in an instant", but I do agree to some extent.
Before this exploit, it would take over 13 hours of grinding in order to afford the most expensive car(s) in GT7, and that assumes that one only focuses on repeating the very small handful of high payout events.
As I've said before, I've played the game on average an hour every day for 18 months now, and I still do not own a single 20,000,000 Cr. car. I do now have the credits (finally) to buy one, but that involved an extra 5 hours of gaming on top of what I otherwise would have done.