Quackery is already illegal in many places, it did not lead to a 'ministry of truth' or equivalent.

Quackery in what sense? It is my understanding that to be a quack in a legal sense one must first be a licensed doctor, and malpractice is covered by freedom of speech. But you referred to celebrities practicing "quackery" which I assume means that they were saying the same nonsense that could get a doctor's license pulled, and that is absolutely covered by freedom of speech.

Also, you have already admitted there is a Ministry of Truth equivalent, as such a thing is necessary to prosecute people for telling lies.

Quackery:

Dishonest practices and claims to have special knowledge and skill in some field, typically medicine.

The legal definition does not require one to first be a licensed doctor.

And malpractice is definitely not covered by freedom of speech.

Not everybody lives in the USA.