People ignore and negate youth contributions to culture the same way they ignore and negate those of blacks and women.
They say: it doesn't sound like something a child would write;
it doesn't look like something a teenager would paint;
only adults would think of dimensioning clothes like that;
the theme of this movie is too mature.
They say: surely it's the parents who are doing the writing, like some implied Gigabyte's husband was the one who programmed her viruses.
They say: you know, X said s/he was young too, but in the end it was an hoax so that person is obviously one too.
Hey, does James Tiptree, Jr. being a female prove no male writer is really a male writer?
When it's proven they are what they say they are, people mock their works as too childish even though similar works and ideas from adults are praised.
When their contributions are finally recognized, people will minimize these as a "great analysis of being a teen/kid".