I am in no way justifying that toe/heal rule, but I bet I know why they implemented it and that is to avoid having to decide whether the toe or heal (whichever one is in bounds) touches before the other side touches (out of bounds).
In some cases, it is obvious such as what just happened but I can see a lot of cases where it is much closer and very hard to judge.
I still think it is stupid to use a blanket rule like that when it is clear the toe touched down first in bounds.
#reality