Yes, they can be extra dangerous if they have, say, a curious dog on a long leash on the other side of said trail while they’re busy counting Facebook likes
Ah, you must be related to the person from the other day who told my TEN-YEAR OLD to get off the sidewalk because it's illegal.
By the time he rode back and shakily told us what had happened, I had no choice but to inform her at the top of my lungs (since she was 600ft down the path) that, no, it's legal if you're under 16 (in our state).
I’m sorry you were held down and forced to scream at someone two blocks away in public. Hopefully somebody some day will invent a kind of faster-than-foot travel you could use to catch up to someone instead.