You get free 5aps for each job change you do. I'm not sure if this is intentionally there or just an overlook. It's easily abusable (?).
This "issue" has already been established in the past, and to my knowledge, no it is not intentional. However ask yourself this:
Would you rather take your time for god knows how long to spam '@adv > enter' 100 times for 500 ap, or would you rather get 1 rebirth?
brb spamming '@adv > enter' 100 times
It's actually @adv > down > enter, since job changing into beginner doesn't give you AP