The relevant part is that they moved from another city to Munich, which means that certain company taxes would be paid in Munich instead of Unterschleißheim (the city where the HQ was located previously). This means a increase of tax revenue for the city of Munich of tens of MEUR/yr from this tax alone, without even considering secondary effects.

The small physical distance just means that this would be quite cheap for Microsoft to implement, compared to trying to pull the same stunt with another city.