Ya... what you said is logical but if this is how the bank operates, that's it la, time to switch bank  ... Maybank does have such rule though.. last time use to hold their co branch cc and then apply maybank2card easily..

I choose petrol + grocery + mobile(default)
Rest are done by my MBB dual cards.
My total monthly spending are only rm1000 or lesser most of the time.
But all people need to buy grocery, so I fill the quota by buying Top detergent(2.5kg) for rm9.90(after rebet about rm9.10) and sell back at rm9.90 also. So in actual, I'm getting each month rm100(total rm1000 spent) + rm8(sold 10 bags a month)