So first this isn't the shoe to walk for hours. It is when you have slippers at the door and annoyed that they always facing the wrong direction ( sure you also can leave them at 90° ) however like for sauna it just doesn't matter and you always can slip in right away.
You may think this can't work but when walking stairs or sprint you only use the ball of your feet and also people with high heels - so in general feet are designed that way, but for long walks or standing still it is more efficient to roll over the heel. But most animals are also just tiptoeing all the time (unguligrade).
The author marked this model as their own original creation.