The libertarian attitude only works if you assume everyone is equal. Children are not. And because access to knowledge and wisdom (which includes when and how to seek out knowledge, usually passed on by educated parents.) huge portions of people can be left in a semi-childlike state. Tendency to violence, under-appreciation for exponentials, etc...
The role of parental systems is to mitigate the issues of orphans who become disenfranchised. Entire races can be orphaned from traditional values of they were severed from their cultural root. (slaves) the elderly also often become orphaned and so are a big target for scams.
Excessive and imposed "family" is just a cult but that doesn't mean family values don't at a role in functioning society. There is a limit to individual ability.
The role of parental systems is to mitigate the issues of orphans who become disenfranchised. Entire races can be orphaned from traditional values of they were severed from their cultural root. (slaves) the elderly also often become orphaned and so are a big target for scams.
Excessive and imposed "family" is just a cult but that doesn't mean family values don't at a role in functioning society. There is a limit to individual ability.