There are a couple of things that are not very precise in the article. First of all the history of modern Italian is not quite right: standard Italian actually comes more from the dialects of the center, especially Tuscan and there is literature in standard Italian that far predates the unification of Italy (for example the 14th century Petrarca is still perfectly intelligible by contemporary high school students.

The other thing that is overly simplified is that taxes from the wealthier north are really not the cause (or at least not the single cause) of the emigration from the south. Many regions were really poor and not yet industrialized at the turn of the century and not only in the south (Friuli in the northeast was also very poor). I think the main cause of emigration is really lack of employment opportunities and the destinations of these emigrants have been many: there are huge Italian communities in Argentina, Brazil, Germany and Belgium for example.