The basic idea behind the parents argument is that you cannot own knowledge.

There are several arguments for this idea, and massive challenges to overcome if you actually try to act on this idea. One of these challenges is how authors and similar content creators could possibly make a living in a world, where everything they produce can be copied by anyone. There are several thought experiments which try to address this problem, none of which have been successfully implemented large-scale in real life (at least to my knowledge).

but the fact that challenges arise from such an idea does not discredit the validity of said idea. it just means that we haven't found a sustainable way live by that ideal