The foundation of things

In a conversation I recently had with my oldest son (20 years), we discussed the problem with the Harry Potter stories.  Initially, he was under the impression that I argued that the problem was simply the presence and promotion of magic.  But this is far too simplistic and shallow.
As I explained, the problem is in the foundation.  A comparison was made with the Percy Jackson stories.  For those who don't know, Harry Potter stories take place in a magical, hidden world in and through modern day London.  Harry is a young man who initially doesn't know that he is a magician.   He is brought to Hogwarts, a school for magic. 
The Percy Jackson stories, on the other hand, are about a young man who is half human, half god, as in Greek mythology, but takes place in modern day America.
Here is how I perceive these two stories.  The Jackson stories are written as fiction, with a foundation which no one embraces as true, with a story that is clearly make believe.
The Potter stories on the other hand, are built upon the foundation of modern day witchcraft.  JK Rowling, the author, blatantly admits having carefully and thoroughly referenced books on witchcraft from which to build her stories.  The storyline is then created upon this foundation.
I hope you can see the problem here.  The Potter stories are built upon a foundation of supposed truth.  The Jackson stories are not.  The Potter stories present the worldview of magic as valid, noteworthy and beneficial.  It presents reality as built upon impersonal power, that can be used for good or for evil. 
The problem with Potter is the worldview that is presented.  The fact is that interest in witchcraft among the young has greatly increased, while interest in the religious beliefs of Greek mythology has not.
This is about foundations.  The silliness of the Harry Potter stories are only silly when understood as completely fictitious.  Unfortunately, the author and much of the audience don't see it this way.  Therefore the danger of falsehood does exist.
Then there is the whole question of bad influence.  But that is a whole other argument.