Youths lack judgment, so they can’t vote, drink, drive, have sex or consent to adults.
A 14-year-old can’t be relied to understand the consequences of making nudes of some girl.
Beyond that, we regulate guns, speed limits and more according to principles like “your right to swing your fist ends at my nose”.
We do that not only because shoving kids into jails is something we want to avoid, but because regulating at the source of the problem is both more feasible AND heads off a lot of tragedy.
And again, you fail to acknowledge the investigative burden you put on society to discover who originated the photo after the fact, and the trauma to the victim.
If none of that computes for you, then I don’t know what to say except I don’t place the right to generate saucy images highly enough to swarm my already overworked police with requests to investigate who generated fake underage porn.