>0-3 yrs old
Seems extremely strict.
>3-6
Makes sense to me.
>6-9 yrs old
Seems naive. There's no "internet safe zone" where a cess pit is not a query away. (in the case of algorithmic feeds, the cess pit comes to you automatically!)
>9-12 yrs old
A gateway drug to a lifelong addiction, encouraged by all of society to include teachers at school.
>12
Probably still too lax given that 12 is when boys discover pornography.