More generally, has there even been such systemic discrimination between Italians who originate in the south? I am also wondering the context of this image:
He certainly said it.
From the New York Times: After Argentina's quarterfinal victory over Yugoslavia on Saturday, Maradona tried to lobby for a little divided loyalty, reminding Neapolitans that they are often regarded as ''southerners'' or even foreigners by the northern industrial and political power in Italy. ''The Neapolitans must remember one thing,'' Maradona said. ''Italy makes it feel important one day of the year, but forgets about it the other 364.''
I'm afraid I'm unable to answer your other questions.
the context of this image:
It reads: "Maradona, Naples loves you, but Italy is our nation"
