For some reason Apple's cables are all pants, I have a split in my Macbook charger where you do. Loads of people on the net have documented it and even provided guides how to repair it yourself. There are also third party products designed to reinforce that area of the charger. If that's not a sign they aren't up to the task at hand, I don't know what is.
The exact same thing happens to iPhone cables, I have lost count how many I've replaced over the years, none of my old phones from other manufacturers ever had a problem.