For chemical and nuclear weapons, it makes more sense that they are restricted, because they are explicitly weapons. They have no benefit. The technology that underpins nuclear weapons does have benefit, and there are many nuclear reactors in the world. I don't know very much about chemical weapons, but I am guessing that the same chemistry discoveries that enabled chemical weapons has also gone into making useful chemicals or medicine.

For CFCs, we realized the negative impacts, and successfully internationally coordinated to stop using them. This happened after it became clear that the real harms that were actively occurring were not worth the benefits.