I think kids tend to do it in traditionally adult spaces just as a buffer from the extreme criticism that can exist online. Saying, "someone wrote a cpu guide" has a lot less impact than saying "a teenage girl wrote a cpu guide". I don't think the individual behind the content is all that important and we have to recognize that we only ever see the kids that tell us they're kids, i could be an 8 year old prodigy for all anyone knows.

Praise is nice, especially when you're young. Stating your young has to dramatically increase praise to criticism ratio in adult spaces like this. No one would care on reddit but we're all old men here lol so the kids stand out. It can be overdone if the person makes the content about themselves instead of the content, or intentionally starts controversy. But this is fine.

Since she states she won a hackathon she's probably a very gifted and motivated young person who is still surrounded with adults telling her she's great, that doesn't mean they're wrong. And sooner or later the adults begin drastically raising the bar for praising you so it's cool for her to get her last couple years out of it.