You implicitly assume that age is a proxy for ability, but that's not the reason for these laws. Age is a proxy for membership in a social class where discrimination is permitted. Otherwise we would prevent people from voting, which Americans did with Literacy/IQ tests and Blacks.

The actual reasons is that they hope to have captured the childs' reward system by then. Laura Cress must write articles for the BBC if she stopped she would lose her purpose in life and be forced into rehab, she would experience ego death and ostracization until she builds another system approved skill. Current society is heading off a demographic collapse due to this built up debt.

The real problem is that we have invented a society that is less rewarding than a slot machine, not that humans are somehow built wrong. A slot machine or hard drug can only effectively hack ones physiology, a social system can hack the whole stack at once (Physiology, Emotions, Ego, Social belonging). You can give bad actors the pains of withdrawal, peril, existential crisis and social suicide all in one. There are examples throughout very recent history of each layer being captured more perfectly. Even physiology more perfectly than any drug, think enclosure act, 14 hour workdays in industrial England.

Fine, ban lootboxes, but don't pretend it's to protect youths, it's to utilize "children". society is a massively harmful and evil tool, we must acknowledge that it's pure unadulterated evil that wouldn't blink at killing all youths. This is a fact, not an opinion, morals are just an API for humans that the system uses.