Well, think about it for a minute. In the eyes of all the world, a trust is supposed to be an arrangement whereby someone entrusts assets with someone else to be held in safekeeping for some future purpose. If the grantor were also the trustee, that means someone is entrusting those assets with himself or herself. It is just common sense that anyone anywhere would see that as absurd and meaningless. Thus indeed, it is considered to be a sham in the trust world. It is not really a trust. If someone were to create an entity like that, it could fall apart very easily with the very slightest wind of challenge blowing by.
Our Natural Law Trusts are invincible and bullet-proof precisely because they adhere to the commonly recognized universal protocols of trust integrity.