While some do, in order to increase their credibility, there's also a lot of survivorship bias/selection bias. There are a lot of projects (or comments) by teens that don't disclaim their age.

I know I don't mention my age because I want people to judge my work objectively. (not to imply that I'm a teenager...)

And he's been working on it for a year. So he built a web framework at 14.

And I can't center a div without a google search...

(I am a back-end dev tho, so its a little better than it sounds)

Can't see they did it here, though. You have to click into their profile to see it.

Probably safest to avoid people raining hate in them for any perceived falling.