Earlier quoted context omitted.
As an absurd example, if someone were to invent a ray-gun that reprograms people's brains with arbitrary beliefs it would be 100% unethical and illegal to use. However, ads or fake news article that takes many exposures to reprogram you (by using the cognitive bias back channels as you mention) are perfectly fine. ¯\_(ツ)_/¯
With the raygun there's a clear cause and effect. You can fairly easily prove that what changes beliefs is the raygun. You can't do that with ads and fake news articles. The other point is that with ads and articles you have to engage with them yourself. Something can grab your attention, but you can decide to ignore it anyway.
That's a slippery slope, when we remember that researchers are constantly looking for the right hooks that edge the 'persuasion' closer to entrapment.
Doubly so when we consider neuroatypicals; While many people think of a 'seizure' as something that results in shaking movements/etc, There is a nonzero size of the population that can have seizures that are more 'internal'; the stimulus results in either a locking of focus on an item, or a sort of disoriented haze (at which point, for some, their subconscious is wide open.)
Those who take the time to study hypnotism/NLP and are more wise than intelligent understand that we are playing with fire here folks.