… yeah, but sorcery actively involves demons. Obviously, being commanded by God to do something makes it clear that the action itself, by its accomplishment, will not endanger a person spiritually. Therefore, it’s perfectly legitimate to see God require a religious rite that, outside of His promised protection, would be absolutely forbidden due to its great dangers, and which would therefore be sinful to engage in without His permission. A great, modern-day example of this is a solemn exorcism. God gives protection to His priests, when they have faculties from a bishop, to perform a solemn exorcism. But if YOU were to attempt that same solemn exorcism on a possessed person, you might find yourself getting thrashed or worse.
Furthermore, it’s pretty clear, considering his gross errors, that Joseph Smith was not actually commanded by God do much of anything, and certainly not to use “seer stones.” In fact, his dabbling with such things may very well have exposed him to demonic influence, which brings us back to why such things are forbidden in the first place.