AFAIK, permaban is for plagiarism, spam boosting, and ban evasion.
Begging spam deserves a temporary ban, usually 7 days for first offenders.
What happens if he/she gots a temporary ban, or even a permanent ban?
Nothing special... If he/she don't need that username, he/she just registers a new one and will continue the spam/begging...
What we need is reporting, if people report these kind of posts and mods will delete them, spammers/beggers will just slowly stop and go away... hopefully...