Do all stories need to be of virtue and success?
It seems like you're disappointed it wasn't a modern "noble savage" myth, that it was realistic instead of a fairy tale about a person coming from a bad place to a good place and being happy, wholesome, and free.
This kind of mythology is a pretty big problem in the western world right now as is the kneejerk reaction to it.
That’s a rather uncharitable take on what the poster you’re responding to wrote.
I read Persepolis a few years ago, and it’s hard not to come away with a similar impression. The first part often does resemble a fairy tale of sorts, while the second part is a pretty dark story of teenage alienation. The contrast is jarring, and it goes well beyond “duh nobody’s perfect”.
Both parts are excellent in their own right, and quite unlike any other book I’ve read, but there is indeed something strange going on in part 2. Most readers will remember this, I think.