I would guess you'd just want to get faster growth.
Why wait ten years busting your ass day-in day-out in the gym with dialed-in nutrution when to had an impressive amount of mass while you could do it in 2 with a couple of AAS cyles.
Unless you go under the teens and you are sure you've finished growing, I have difficulty finding a reasonable, physiologically-defendable reason why you could not take AAS.
I've seen a number of people using steroids to reach and breaktrough what you'd expect be their genetic potential. They don't seem to be all that worse for wear.