The biggest flaw is baked into the system... credit cards generally make everything cost a little bit more because vendors bake the processing fees into their sale prices. You may get a small percentage of your expenditures back from your credit card, but not nearly as much as the mark-up you've paid. The effect is a tax on yourself and everyone else. The tax is worse on those who don't use credit cards because they don't even get a partial refund.

The law used to be that you could offer a cash discount, but you couldn't charge extra for using a credit card. That law changed and now many places are adding a surcharge if you use a credit card. You might note, however, that prices didn't go down 3-5% everywhere. So now the retailers are double-dipping... they have the credit card fees baked into their pricing and then they're having those who use credit cards pay the fee explicitly.

I still think there are solid cases for using credit over debit if you are able to pay the bill in full every month to avoid any interest and late fees.