Where are all these poisoned children getting the cash to buy these things?
This is a short sighted and unaware comment.
It starts with desire.
And carrying it regardless of whether there is money or not.
And what the feeling of lack in an impressionable child can do.
The fundamental issue is unmanaged exposure to devices and content does harm to children.
"I can surround your child with dangerous unhealthy things and do my best to corrupt and poison them, there should be no limit to this behavior whatsoever because if I succeed it's your fault for being bad parents! All you have to do is say no, it's not like it's my full time job to make end-runs around you with the aid of behavioral science and psychology and a budget, no no no guiding your children morally is as simple as saying no once, are you too stupid and lazy to do that?".
"Parents should just say no" is another extreme.
I would put money on the best solution being somewhere between those two extremes.
splwjs says that corporations have the responsibility because they spend billions on psychological manipulation campaigns.
Your view of the world lacks much nuance.