That is another way of using this card - stop using it when it reaches the annual 5k mark. However, the hassle still exists, and it is even more complicated than the monthly situation.
For the first few months, it is fine and it is still far away from the limit. But sooner you will start feeling it is close and sum up all the numbers for the past months and remember it, add the future purchases on top of it to avoid passing that line. That's just too much. Even though the annual fee can be waived with the AI account, this card just makes your life more complicated lol...
I have a feeling TD totally can launch a 4% card similar to CIBC/Scotia, but they decided not to do that because the annual fee can be waived by the AI account, and they can fool customers to keep/sign up AI accounts in this way.
A lot of 5k dead money in their hands, well play, TD.