We live in an intergenerational world.
Kids are not isolated creatures being raised in bubbles to be unleashed onto the world at 18 years of age and it would be wrong to do so because they’d be unprepared.
At the age of 5 years old, they are sent to concrete boxes with other children who will be future thieves, murderers, politicians, ceos, plumbers, electricians, gamers, etc and they have to learn to deal with that cacophony of personalities.