You could not be more wrong. A billboard is non-interactive. It can never make full use of any of the psychological blindspots inherent in people whereas the experiment was entirely interactive.

You are aware that your stated opinion of social experimentation includes outcomes that historically are found in cults, and torture, and had outcomes of death right? You completely neglect that in your argument to support this. The Jonestown massacre as an example.

Are you familiar with the coercive double bind of Sophie's choice?

The way it goes...You have a choice, to kill one of your children by sending them off to the gas chamber, your son or your daughter, but in so doing you will save your other son or daughter, if you make no choice both die and so do you.

You are isolated, it is just you and your children you can't get help. You cannot remove yourself from the choice. There is perceived loss that may become real loss, you won't know until you make the choice. There is the cognitive dissonance in that your identity as a parent is protective in nature but you must violate that to remain internally consistent to protect the other. The survivor will know you made the choice. There are multiple structured trauma loops.

This described situation falls under social experimentation. It also meets all the classical requirements for real-world torture which is simply the imposition of psychological stress through elements, structuring (trauma loops), and clustering (in time of these things).

Yelling at the clouds will not make the world a better place by itself, sure, and inducing people to mental breakdown, and other related psychological and physiological responses that arise and form issues precognition that come with torture are far worse, which you neglect or simply don't know.

Indoctrination of youth includes torture during a period of vulnerability in their development which crystallizes their thought processes moving forward in life. This also falls under social experimentation. It need not be physical, you can inflict these things on others socially through structure and word through communication. This is the basis for propaganda which many don't even realize they've adopted internally.

A loud or short series of pops is heard near a school. If your immediate first thought was school shooting, that's a mild indoctrination. A car backfired, or some kids lit some fireworks, far more common but not enough to warrant being on the news (distorted reflected appraisal at work).

Operant conditioning towards stimuli caused by a constant barrage of curated media can have lasting harm to self when done for purpose.

The same goes for a lot of other things, often towards disunity, people rarely reflect on their first impulses, and if you don't have critical attention in those impulses they simply follow set patterns robotically which is thoroughly described in classic material on this subject matter (Joost Meerloo and Robert Lifton).

If you distort the inputs and shape the mind into a parasitic structure for purpose towards a non-adaptive control, this causes societal systems to fails over time the brittle bridge breaks under stress. The flexible adaptive solution is resilient.

This goes to the heart of the differences between Proteanism and Totalism cultures.

In the latter you get a lot of doomed people who can't reason or think, and by extension lack the critical gift that elevates humanity over animals. These types are already dead, they just don't know it yet, and simply wait for the right set of circumstances to arise that will domino to extinction, as occurs more often than not in dystopian fiction.

Anything related to the protection and assurance of the dependencies you need to grow, self-direct, and survive are a serious matter to the living.