There are places that are underpopulated and really need to get people with talents to move in. There are cities that want to attract businesses. What a better way to show a great city than Instagram. Brochures and advertisement are nowhere as reaching as Instagram. They can also be used to get more vacationers. It is helpful to show places and things that make the city special and different from other cities.
Pictures are very different than words they really can make a place look interesting to someone that does not live there. There might be a need for doctors or nurses to come to the city and open a business. They might be able to show the structure that they have for them and the need by showing the people of the city.