I suppose you're right. It is possible. It's just that too many OTs have what I call the "Satoshi Complex". They're irritatingly immature and carefree, they have parents that apparently don't care, and nothing ever happens to them. They never get mugged, they never run into much serious trouble, and when they do (evil team much?) they blow it off with little trouble, occasionally dying and coming back in the process. Seriously, if I was Delia Ketchum, and for some reason had let Ash go off to be a Pokemon Master, I would have brought him back home straight after Mewtwo Strikes Back and never let him leave the house again. I'm in high school, and my parents are unsure about leaving me at home alone for an evening.
This is of course assuming that Pokemon characters are human like us. If they are some form of carbon-copy race with no parental instincts whatsoever, the point is moot.